A rough guide to what's new in Windows 8, how it differs from Windows 7, and whether existing Windows users should upgrade to Windows 8.

We now know that Windows 8 will launch in October, in both its X86 and ARM Windows RT flavours. And we expect Windows Phone 8 and the Microsoft Surface tablet to launch at around the same time.

If you are looking to upgrade your smartphone or tablet, then, Windows 8 will offer a very different alternative to Android, iOS and the rest. But what about the majority of the world's one billion Windows users, who are running X86 Windows PCs and laptops? Here then, is a rough guide to what's new in Windows 8, and how it differs from Windows 7. See also: Windows 8 uncovered: a deep dive into Windows 8.

Windows 8 vs Windows 7: Metro interface and touch

The most immediate and fundamental difference between Windows 7 and Windows 8 is the main interface. Although the Desktop view is similar to traditional Windows, most of the time you'll be interacting with Windows 8's Metro interface - and boy will you notice the difference. The Metro interface is the default home screen for Windows 8, and features a series of colourful tiles, each offering access to a discrete application. Each offers live information, so you can see how many emails are in your inbox, for example, without having to open an application. You can customise your device's Metro interface, adding for instance access apps, web pages, images and even people - or at least their picture, contact details and your combined communication.

Metro is bold and striking to look at, and you can change its colour scheme to suit your taste. You can also log in to an account, and take your settings and apps with you wherever you roam, similar to using your Google account with Android. Metro is scalable, too: so if you zoom out the tiles rearrange themselves in a meaningful way.

Windows 8 touch or type

It's sure to attract as much criticism as it does praise, because Metro is so very different from what went before, but Metro is certainly new to Windows 8. It's also designed to work best with touch-enabled devices, so if you are running a Windows 7 PC without a touchscreen, you may decide that the change is not worth it. There's a lot of dispute about the potential value of touchscreen PCs and laptops, and it is indisputably true that touch is not ideal for typing on an upright screen, for instance. But if you do have a touch-enabled device, you may find that you interact with a Windows 8 PC using your digits a lot more than you expected to.

With our Windows 8 Slate and Bluetooth keyboard setup we find that we've been using the keyboard to type out emails, for instance, but touching the screen to hit send. Windows 7 has touch capabilities, of course, but it's nothing like a true touchscreen OS: with the Metro interface. Windows 8 with Metro is. See also: Windows 8 Tablet review. For more on the changes in Windows 8 and how to use them visit Windows 8 Advisor. For detailed advice on installing Windows 8 Release Preview, read our article: How to install Windows 8.

Windows 8 vs Windows 7: Windows Store and Apps

The Metro interface looks and feels like a smartphone or tablet OS, and following that theme is the inclusion of the Windows Store in Windows 8. This online shopfront is stuffed full of Windows apps - each designed to run on x86 Windows PCs, laptops and tablets, as well as ARM tablets and smartphones. Windows 8 apps follow the same design principle as Metro - being constructed of cascading live tiles of information, in primary colours. They all have social networking capabilities baked in as standard, and follow the same principles of interface, so that there is no real learning curve when starting to use a new app.

Native apps included with Windows 8 include the Mail email app, a calendar app and much improved contacts app called People. There's Photos, Music, IE, Weather, Finance, Sports and so on. Which is all very nice, but if you are an existing Windows 7 user wondering whether to upgrade, you almost certainly have legacy X86 software programs that you wish to continue to use. This is taken care of in all flavours of Windows 8 apart from Windows RT and Windows Phone 8.

Windows 8 Tweetro app

To use older software in windows 8, you have to use Desktop. This is an app in its own right, and opens up into an environment that looks and acts in virtually the same way as Windows 7. Think of it as virtualised Windows 7, in Windows 8 (it's like a much more simple version of Classic Mode from when Mac OS X first came out). This is imperfect, of course, as it means that much of your computing expeirence in the 'new' OS is taking place in a window that looks suspiciously like your old one. Still, it's difficult to see how else such a great leap forward in Windows' interfact could be handled. And it does mean you can have the best of all worlds.

The Desktop mode in Windows 8 is different from Windows 7 in one subtle but critical way, however: there's no Start menu. In fact, wherever you are in Windows 8, either touching the middle right of your screen or mousing over there brings up the Charms menu, which comprises Search, Share, Start, Devices and Settings icons. The change takes a bit of getting used to, but is actually a lot more straightforward than the old way of doing things.

According to Microsoft Windows 8 is designed to be used by touch, keyboard and mouse - whatever is most appropriate to the task in hand. The corners of the screen are easy for mouse use, for instance, which is why the Start 'button' has disappeared, and in order to get to the Start menu you simply mouse to the bottom left. Similarly, for mouse users 'back' is top left, and to get to 'Charms' you have to go to the right and swipe. Keyboard navigation has been similarly adjusted. To get the 'Weather' app, for instance, you simply type 'weath...' and as you type the options will reduce until the Weather app appears. Meanwhile, page up, page down and so on, work as they do in Windows 7.

You can access search from anywhere, and the results are listed via the icons of the apps in which they appear. Simply click an app to choose results from that application. A search from anywhere combs the entire machine.

There are, of course, some down sides in these changes and to the fact that older software works only in the Desktop mode, but compatibility with other Windows 8 devices isn't one of them. For the price of getting used to some new interface tricks, you get to run all of your new apps across all kinds of Windows 8 devices, including PCs and laptops, but also ARM tablets and smartphones - in an interface that looks the same and has all your settings regardless of which device you are using. (See also: Windows 8: the complete guide.)

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