Microsoft releases the new Virtual PC 2007 today and guess what? It’s a free application. Unfortunately for Mac users you wont be able to get this new release. Microsoft only developed Virtual PC 2007 for Windows only and supporting both Windows 32-bit and 64-bit.
Supported host operating systems are Windows Server 2003, Vista Business, Vista Enterprise, Vista Ultimate, XP Professional, XP Professional x64, and XP Tablet PC Edition.
Supporting guest operating systems are Windows 98 Second Edition, 2000 Professional, XP Home, Professional, Tablet PC Edition
Vista Enterprise, Business, Ultimate, OS/2 Warp Version 4 Fix Pack 15, OS/2 Warp Convenience Pack 1, and OS/2 Warp Convenience Pack 2.
Although not officially supported, MS DOS 6.22, Windows 95, 98, ME, and NT 4.0 Workstation should be able to run. So go and grab a copy for yourself.