CWmike writes "Microsoft's decision to let Windows 7 users run Windows XP applications in a virtual machine may have been necessary to convince people to upgrade, but it could also create support nightmares, analysts said today. Gartner analyst Michael Silver outlines the downsides. 'You'll have to support two versions of Windows,' he said. 'Each needs to be secured, antivirused, firewalled and patched. If a company has 10,000 PCs, that's 20,000 instances of Windows.' The other big problem Silver foresees: Making sure the software they run is compatible with Windows 7. 'This is a great Band-Aid, but companies need to heal their applications,' Silver said. 'They'll be doing themselves a disservice if, because of XPM, they're not making sure that all their apps support Windows 7.'"