Computer buying guide

Computers come in a variety of shapes and sizes, from all-in-one desktops to convertible laptops. They include various different features and functions, and with so much available it can be hard to distinguish which one is actually right for you.

There have been great advances in technology over the last few years, with a new computer being up to three times faster than a 4-year-old equivalent in everyday performance, with much improved graphical abilities and start-up times. Whether you’re buying your first computer, or simply replacing your old one, this guide is here to help you pick the right option for your needs.

Choosing the right device

Choosing the right type of device is the first thing you’ll need to do. There are various options available, whether you need a powerhouse for working at home or something that you can take with you on trips away.

Computers by function and form

Computers by function


To make your search simpler, John Lewis categorises our computers into five functions:

Everyday computers are designed for basic home use and web browsing. They may not be the most powerful computers, but they’ll get most people through everyday computing processes.

Performance computers are aimed at high-end users, who need to have multiple advanced processes open at once, such as video and photo editing programs. These machines will have a top of the range processor and a large amount of RAM.

Gaming computers are hugely powerful computers with a dedicated graphics card and large screen in laptops and all-in-ones, as well as a high-end processor and large amount of RAM. These machines are ideal for playing the latest computer games.

Ultramobile computers deliver powerful performance in a portable package. They have long battery lives and are ideal for intensive users who need to travel with their computer a lot. 

Remember, our filters are here to make it easier to find the right one for you and can you can mix and match the features you need, so it shouldn’t be too difficult to find an ultramobile performance laptop or a gaming tower.

Computers by form

Towers are desktop computers without any additional components, such as monitors and speakers. They come in a variety of sizes, including space saving small form factor models. You’ll also find that you’re likely to get more power for your money with a tower, as they're cheaper to manufacturer- however, don’t forget you’ll still need at least a monitor to be able to use it.


All-in-One Desktops combine computer, monitor and speakers into one unit. They’re a much less intrusive proposition than a tower and monitor combo, doing away with many of the additional cables required. Many of them also feature touch screens, making them perfect for navigating Windows 8. They’re ideal for watching films and performing graphical work, thanks to their large, high quality screens. 

Apple iMacs were some of the first all-in-one computers in the mainstream market. 

Laptops or notebooks, cover a wide range of portable computers. They feature a ‘clamshell’ design and have an integrated keyboard, mouse and display that can measure up to 17.6-inches in diameter. 

Ultrabooks are the ultimate lightweight, all-purpose mobile PC for travel, work and play. Powerful performance from Intel Core processors, wakes up in a flash and has battery life that lasts. 

Chromebooks are fast, simple and secure web-based computers running Google’s Chrome OS.

MacBook Pros are powerful laptop computers made by Apple and running Mac OS X. Some of the newer models feature an ultra-clear Retina display.  

MacBook Airs are lightweight, portable equivalents to the MacBook Pro. They also run Mac OS X and include fast flash storage. 

Convertibles are devices that can convert between portable computer and tablet by removing or hiding the keyboard. Also see Convertible Ultrabook. 

Tablets are handheld portable computers that primarily use a touch screen for navigation. They run on a variety of operating systems, from Apple’s iPads on iOS, Google Android based systems or Windows devices. For more information on tablets, please see tablet buying guide and guide to tablet operating systems.

Choosing an operating system

The operating system is the basic software that controls many of the computer's functions and also acts as an interface between the user and the microprocessor. There’s a perennial debate over whether it’s better to purchase an Apple Mac computer or a computer running Microsoft's 'Windows' operating system. To complicate things further, Google have recently entered the fray with their Linux-based Chrome OS. Each system has its strengths and weaknesses, and they all have their fans.

Microsoft’s Windows operating system is the most widely adopted system in the world. Windows laptops are available in a variety of sizes and capabilities, from simple everyday laptops to powerful gaming desktops.

The newest version, Windows 10, builds on Windows 8 by integrating the start menu with the start screen. Windows 10 is designed to be cross-platform - that is, one operating system, tailored for your device, whether it’s a PC, tablet or smartphone, with apps created to run across all three. It also includes Cortana, your own personal assistant,  and a number of enhancements, such as the Microsoft Edge web browser.

Windows 10 is compatible with all Windows 8 devices, although some new functions require specific hardware requirements, such as dual microphones for Cortana. 

Find out more about Windows 10


Chrome OS

Google’s Chrome OS is designed to be a fast, simple operating system, ideal for people who are on the go and need to access their work from various machines. Chrome OS utilises web apps - programs that are accessed over the internet, with any saved changes you make to documents being stored in the cloud - and accessible from any other internet connected device. Chrome OS automatically backs up your work to the cloud so there’s a smaller risk of you losing it. It also includes built-in virus protection, making it easier to keep your important files safe.

Take a look at our Chromebooks and Chromeboxes.

Mac OS X Mountain Lion

Mountain Lion from Apple is designed to run exclusively on Apple’s range of Mac computers. Famed for its clean and intuitive interface, OS X uses a dock at the bottom of the screen to give you quick access to your favourite apps, with the ‘Launchpad’ icon giving you full access to lesser-used apps. It features built-in security against viruses in the form of ‘Gatekeeper’ and features innovations such as iCloud, which will sync your content with other Apple devices - iPods, iPhones and iPads - using the same Apple ID to make keeping your digital life in sync easier than ever.

Take a look at our MacBooks and Mac desktops.

Mac OS X Yosemite

Yosemite from Apple is designed to run exclusively on Apple’s range of Mac computers. Famed for its clean and intuitive interface, OS X uses a dock at the bottom of the screen to give you quick access to your favourite apps, with the ‘Launchpad’ icon giving you full access to lesser-used apps. It features built-in security against viruses in the form of ‘Gatekeeper’ and includes intuitive gestures to make it quicker and easier to get around. Finder is used to browse and organise your files, with Spotlight ensuring that searching for documents and apps is effortless. It comes with a number of apps like Pages, Numbers, iPhoto, iMovie and Garageband that give you the platform you need for productivity and creativity, with more great apps are available for download from the App Store.

If you own and iPhone, iPad or iPod touch running iOS 8, then Yosemite includes clever enhancements to help you move seamlessly between devices. Make and receive iPhone calls and send and receive both iMessage and SMS text messages on your Mac. Start an email, document or browsing session on one device and instantly pick it up on another- Yosemite makes OS X even better for anyone who already owns Apple devices.


What to look for


The Central Processing Unit (CPU or 'processor') is the 'brain' of the computer that drives and controls all its functions. There are a number of different processors from different manufacturers, intended to help you get what you want from your computer.


Intel offer a variety of processors across a range of segments.

  • You’ll find Intel’s Atom processors in smaller laptops and netbooks and will provide powerful mobile computing and longer battery life.
  • A Celeron processor will provide great quality and reliability for basic computing tasks, such as creating documents, and watching videos.
  • Intel Pentium processors offer great value for great performance and are ideal for everyday tasks, from document creation to streaming HD videos.


Intel’s Core family of processors come in three levels:

  • Intel Core i3 is designed to give seamless performance that keeps up.
  • Intel Core i5 will provide excellent performance for users who want to experience everything.
  •  Intel Core i7 is aimed at the most demanding users, providing top-of-the-line performance.

The newest generation of these processors (the 6th generation, or Skylake) provides extensive battery life and optimum performance to deliver a new standard for computing.

AMD provide a similar range of processors.

  • The E-series will provide excellent performance for your everyday tasks allowing you to work, play and live your day-to-day digital life with confidence, inspired by the rock-solid, essential performance and responsive design.
  • The A-series of processors provide fast and responsive performance, and are designed to handle virtually everything you throw at it.

NVIDIA’s Tegra and Samsung’s Exynos processors are designed to provide powerful mobile performance. They’ll often be found in convertible laptops and Chromebooks, as well as in tablets.

Storage space

Internal storage space, or hard drive, is the space where programs, files, data and documents are stored. Hard discs come in different sizes, measured in gigabytes (GB) and terabytes (TB). 1TB is approximately 1000GB, and the more storage you have available, the more room you’ll have to store your programs, documents, music, photos, and videos. Storage space comes in two categories these days: hard drives and flash storage. Hard drives are cheaper to manufacturer and can go up to vast sizes. Flash storage and Solid State Drives (SSDs) offer faster access to your files, but are much more limited in size. 


Often confused with the amount of storage for files and documents, in laptops, memory more often refers to the Random Access Memory or RAM (also known as ‘on-board’ memory). Simply put, the more RAM you have (measured in bytes, and these days mostly gigabytes (GB), the smoother your computer will run when it has lots of intensive programs open at once.

Graphics card

All computers come with some form of graphics card. Some of these - ‘shared’ or ‘integrated’ graphics - cards use the system’s built-in RAM to power its technology. Other ‘dedicated’ graphics cards will include their own RAM built-in to give more powerful graphical performance.

Integrated graphics card, such as Intel HD Graphics and AMD’s Radeon HD ‘G’ Series provide superb visual performance for everyday use, such as watching HD videos and viewing photos.

Dedicated graphics cards, like the NVIDIA GeForce range and AMD’s Radeon HD ‘M’ Series are vital for those who love advanced image and video editing, as well as gamers.

Disc drive

Many computers come without a disc drive, particularly ultra mobile models. However, some still do, and there are a variety of different types to look out for:

  • CD-ROM drive – Will read CDs containing new computer programs, as well as playing music. The drives operate at different speeds.
  • CD-RW drive - 'Writes to' (records onto) a blank CD, as well as reading it. Useful for recording music from MP3 files or CDs, subject to copyright.
  • DVD ROM drive - A format which stores higher data storage capacity than a CD-ROM drive - up to 4.7 gigabytes of data. Plays films as well as reading CDs.
  • DVD-RW drive - 'Writes to' (records onto) a blank DVD, as well as reading it. Useful for burning home movies to DVD.
  • BD ROM drive - Reads Blu-ray discs containing high definition video or data. Will nearly always play and write to CD and DVD media too
  • BD-RW drive - 'Writes to' (records onto) a blank Blu-ray disc, as well as reading it. Useful for burning high definition home movies to Blu-ray disc. Will nearly always play and write to CD and DVD media too.


Laptops come with integrated LCD screens. These are measured diagonally, from corner to corner and generally ranging from between 11 and 18 inches in size.  All-in-one desktops also comes with built-in screens, starting from 20 inches. Tower PCs will require an additional monitor. These screens employ various pieces of technology to try and give you the clearest picture possible. They’ll also come in either gloss or matte finishes, to provide either vibrant, brighter colours or better performance in bright light, respectively.

Internet access

Most computers will come with WiFi (Wireless Fidelity) technology allow you to access broadband internet wirelessly around your home (requires a wireless router). There are also increasing amounts of public ‘WiFi hotspots’ that provide access while you’re out and about.  Some portable computers also include slot for a mobile SIM card, to enable you to connect to wireless phone networks using 3G or HSPA+ data signals.

However, you may prefer to connect to your internet connection through a wired Ethernet port, which will often lead to increased performance. This can be invaluable for gamers and people who perform a lot of heavy duty internet-based tasks, such as streaming or downloading HD videos.

Sound cards and speakers

Laptops and all-in-one computers are equipped with sound cards and speakers so that you can enjoy music and video content directly from your computer. Sound quality has come on leaps and bounds, with technology from the likes of Dolby and JBL employed to optimise performance. However, for the best experience possible, it may be worth purchasing a set of  external computer loudspeakers.

Software and Accessories to consider

Software and Accessories to consider

Most computers come pre-installed with a wide range of software, covering anything from tools to make your computer perform more efficiently to applications for browsing the internet. However, there is additional software available that doesn’t currently come pre-installed on our computers.

Microsoft Office currently only comes on our Windows RT laptops and tablets. There are various different packages available to suit your needs.

Security software is also essential. We stock Norton that is aimed at protecting not only your computer, but your personal information too.

If you’re buying a portable computer, or are looking for something more for your desktop, you may also want to invest in a separate mouse or keyboard. These come with a variety of different functions, with the latest mice for featuring touch and gesture controls to help improve your experience. You may also want to consider an external disc drive if you’re buying a portable computer that doesn’t have one built-in, or an external hard drive for backing up your important data.

More help from us

More Help from John Lewis

John Lewis offers a comprehensive range of services to set up your new computer and products associated with it. These start at simply getting your computer ready to use through to establishing a safe and secure wireless network in your home. These services are currently only available through your local shop, but you can still arrange them even if you bought your computer online from us - you'll just need to produce your delivery note.

All our computers come with at least a 2 year guarantee at no extra cost as standard for your peace of mind. They also qualify for our 90 days free software support helpline. Find out more about our guarantees and the helpline. 

We also offer extended added Care that can be taken out at any time within 30 days of your original purchase; this offers extra protection on top of our guarantee. Find out more about Added Care



 All-in-One: a desktop computer that features an integrated display and speakers. 

Backup: keeping a copy of files and software on rewriteable DVDs/CDs, USB flash devices or external hard drives. Because computers are not infallible, it’s good practice to safeguard your work.


BD (Blu-ray) drive: a drive that can read Blu-ray discs containing high definition video or data. Will normally be able to read video or data DVDs as well as audio or data CDs. With a storage capacity of up to 50 gigabytes (GB) of information, Blu-rays discs can store much more data than a DVD. Many BD drives can also write (record) to Blu-ray, DVD or CD media.


Bay: receptacle for storage systems, such as DVD and other drives.


BD-R disc: a Blu-ray disc that can have data written to it just once.


BD-RE disc: a Blu-ray disc that can be written to and erased and re-recorded multiple times


BIOS (Basic Input/Output System): the BIOS is a version of ROM used in start-up procedures when the computer is first switched on.


Bluetooth: allows you to connect compatible devices wirelessly, such as keyboards and headsets.


Caching: for storing frequently used data in fast RAM connected directly to the CPU.


Compact disc (CD) drive: storage drive for reading CD-ROMs. Comes in a variety of speeds represented as multiples of X, where X = maximum speed of the drive.


CD-R disc: a CD disc that can have data written to it just once.


CD-RW Disc: a CD disc that can be written to, erased and re-recorded multiple times.


Central Processing Unit (CPU): also known as the microprocessor, the CPU is the brain of any computer, controlling all functions and actions. Its speed is measured in megahertz (MHz) or gigahertz (GHz), respectively millions or billions of cycles per second. The faster the CPU, the quicker the machine.

Chromebook or Chromebox: A computer running Google’s Chrome Operating System.

Convertible: A portable touch screen computer that can convert between laptop and tablet.

Desktop: A non-portable computer designed to take its place on your desk at home. See ‘All-in-One’ and ‘Tower’.


Digital Video Disc (DVD) drive: a drive that can read DVDs as well as audio CDs and software CD-ROMs. With a storage capacity of up to 4.7 gigabytes (GB) of information, DVDs can store much more data than a CD-ROM. The majority of DVD drives nowadays will also write to DVD-R, DVD-RW, CD-R and CD-RW discs.


Email: see Internet/email


Gigabyte (GB): standard data measurement unit. One gigabyte contains 1,024 megabytes


Gigahertz: gigahertz (GHz) are used to express the speed of a central processing unit (CPU). 1 gigahertz equals 1000 megahertz (MHz). CPU speeds are increasing as technology improves; faster units have now reached speeds of over 2GHz.


Graphics (or video) card: the card that allows your computer to communicate with your monitor, the video card has its own dedicated memory and is directly responsible for calculating the colour, position and size of all objects on the screen. 3D cards are often a pre-requisite for many of today's best-selling games. Some computers come with a video card already incorporated into the mother card


Hard drive: See Internal Storage.


MacBook: Apple Macintosh laptop, equivalent to iMac, Mac mini or MacPro desktop computer.


Internal Storage: the computer's central storage system built into the computer. The bigger the hard drive, the more applications can be stored.


Internet/email: a network that enables computers to be connected together in a 'web'. With access to the internet you can access data from anywhere in the world for the price of a domestic phone call. The same technology facilitates email (electronic mail), typed messages that can be routed to any email address anywhere in the world almost instantaneously. Emails can also incorporate photos, audio recordings or video.


Keyboard: text input device that converts data into computer-readable format. Used in conjunction with a mouse.

Megabyte (MB): standard data measurement unit. One megabyte contains 1,024 kilobytes.


Microprocessor: also known as the central processing unit (CPU), the microprocessor is the central 'brain' of the computer, controlling all functions and actions. Its speed is measured in megahertz (MHz) or gigahertz (GHz), respectively millions or billions of cycles per second. The faster the microprocessor, the quicker the machine.


Modem (Modulator/Demodulator): a communication device via which the computer transmits and receives data over analogue telephone lines. Used for sending and receiving email and to browse and download information from the internet.


Motherboard: site of all of the internal circuitry for the system. The motherboard is the main circuit board inside the desktop computer, to which all other internal components connect. While it is not an element that can usually be specified, it is important to check it will support any necessary upgrades, such as a faster microprocessor and/or has space for additional cards.


Mouse: a small, hand-operated device that provides users with an intuitive way of moving the cursor and selecting areas of text.


Notebook: another word for ‘Laptop’- a portable computer with integrated keyboard, mouse and display.


Netbook: a light, compact, highly portable and generally inexpensive way to use the internet and email. While not boasting the higher spec of a laptop, a Netbook’s WiFi functionality makes for easy access of the internet while travelling.


NFC: a technology for wirelessly connecting two compatible devices simply by tapping them together. 

Operating System (OS): the software handling the computer's basic functions.


PC (personal computer): desktop 'IBM-compatible' computer - not an Apple Macintosh.


Ports: the physical connection points that allows external devices such as printers and scanners to be linked to the computer.


Random Access Memory (RAM) also known as 'on-board' memory: temporary workspace where the computer holds the data it is currently processing. The higher the amount of RAM, the more and larger the applications that can be run simultaneously. Measured in megabytes (MB).


Read-Only Memory (ROM): permanent memory storage for data that does not change.


Resolution: this is measured by the number of pixels - the tiny dots that make up the overall picture. The greater the pixel count, the higher the resolution and the sharper the display. The size of monitor and resolution you will need will depend on what you will use the computer for. Anyone intending to spend any significant amount of time on the internet should aim for a 15" screen and a resolution of at least 1024 x 768 - increasingly the standard for web pages.


Solid State Drive: See Internal Storage.


Sound Card: the card that generates the computer's audio capability producing all the sounds required for audio tracks, games and so on.


Tablet: Mobile computers that are designed to be navigated through a touch screen. 

Terabyte (TB): standard data measurement unit. One terabyte contains 1,024 gigabytes. 

Tower: stand-alone desktop computer that requires an additional monitor and speakers for full functionality. 

Ultrabook: lightweight, all-purpose mobile PC for travel, work and play. Powerful performance from Intel Core processors, wakes up in a flash and has battery life that lasts. 

USB port: an interface that allows a host computer to be connected to any compatible device e.g. mouse, joystick, scanner, digital camera, printer, personal media player, flash drive, and external hard drive.


Video (or graphics) card: the card that allows your computer to communicate with your monitor, the video card has its own dedicated memory and is directly responsible for calculating the colour, position and size of all object on the screen. 3D cards are often a pre-requisite for many of today's best-selling games. Some computers come with a video card already incorporated into the mother card.


Virtual memory: the part of a hard disc used to store data on a temporary basis and swap it in and out of RAM as required.