Inside Windows 7’s virtual ‘XP Mode’

You can expect to hear a lot about Windows 7’s XP Mode in the weeks to come. You may even want to try it for yourself.

But XP Mode which lets you run a virtual XP session directly inside Windows 7 won’t be integrated into the OS itself – Microsoft will make it available as a separate download in both this week’s RC1 release and when the OS finally debuts later this year.

If this week’s public release of RC1 follows the same pattern as Microsoft’s ‘closed community’ programs such as MSDN and TechNet there’ll be two files that you need to download – expect to find these linked from the same download page as Windows 7 RC1 which will of course be the starring attraction on the Microsoft Download Centre from this Wednesday.

The first is a beta of Windows Virtual PC which provides Windows 7 with a runtime engine based on the Virtual PC 2007 software which Microsoft acquired from Connectix in 2003 and subsequently made free in 2006.

It supports USB devices connected to the Windows 7 host PC launching XP applications directly from the Windows 7 start menu clipboard and folder sharing between the XP session and Windows 7 host plus printer redirection.

The filename for this Windows6.1-KB958559-x86.msu if you’ll be using the 32-bit edition of Windows 7 or Windows6.1-KB958559-x64.msu if you’re running the 64-bit OS. The ‘msu’ extension indicates this file is an update package; it’s also a tiny 4-6MB in size.

The second file you need is the Windows XP Mode installer – a 450MB package containing an OS image of Windows XP as a ready-to-load virtual hard disk image.

450MB gets you a pre-canned ‘virtual hard disk’ image of XP SP3

For the 32-bit edition grab VirtualWindowsXP_32_en-us.msi.  At the time of writing Microsoft’s download site didn’t show the equivalent 64-bit edition of VirtualWindowsXP_64_en-us.msi – instead it erroneously listed VirtualWindowsXP_64_es-es.msi as being English when es-es is in fact the Spanish version. Here’s hoping that someone in Redmond picks up that mistake and the 64-bit en-us edition surfaces by Wednesday!

When all your downloading is done first run the Windows Virtual PC installer. Then run the XP Mode installer which unpacks the 450MB image into a 1GB VHD (virtual hard disk) image of XP Professional Service Pack 3. This image lives in a Virtual XP folder inside the Program Files director and also includes a text file containing the license key for your XP VM.

While you don’t need any installation CD to create your Virtual XP machine your PC will need to be running a processor that supports virtualisation – that means either AMD-V or Intel VT must be on the menu and enabled in BIOS. You’ll also have to have Windows 7 set up as either Professional Enterprise or Ultimate edition (of course we all know that you’re going to go for Ultimate).

Virtual PC can also support other versions of Windows but you’ll have to provide your own installer disc or ISO image.

However Microsoft warns that XP Mode isn’t the silver bullet for app compatibility. “Windows XP Mode does not have 100 percent compatibility with all Windows XP applications” cautions Scott Woodgate director of Desktop Virtualisation at Microsoft.

Woodgate also stresses that  XP Mode is intended for the more straight-forward needs of small businesses rather than consumers and gamers.

“Windows XP Mode is best suited for older business and productivity applications such as accounting inventory and similar applications. Windows XP Mode is not aimed at consumers because many consumer applications require extensive use of hardware interfaces such as 3-D graphics audio and TV tuners that do not work well under virtualisation today.”