Its here .. go get it … http://www.microsoft.com/windows/products/winfamily/virtualpc/default.mspx

Use Microsoft Virtual PC 2007 to run multiple operating systems at the same time on the same physical computer. Switch between virtual machines with the click of a button. Use virtual machines to run legacy applications, provide support, train users, and enhance quality assurance.

Virtual PC lets you create separate virtual machines on your Windows desktop, each of which virtualizes the hardware of a complete physical computer. Use virtual machines to run operating systems such as MS-DOS, Windows, and OS/2. You can run multiple operating systems at once on a single physical computer and switch between them as easily as switching applications—instantly, with a mouse click. Virtual PC is perfect for any scenario in which you need to support multiple operating systems, whether you use it for tech support, legacy application support, training, or just for consolidating physical computers.