From: "John Beamish" 

http://www.microsoft.com/windows/products/winfamily/virtualpc/default.mspx


On the product info page:

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
applicationsƒ ”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.

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