Hi JanineS!
It kinda is part of Windows, but you have to install it. Wich version of windows do you have?
As clifford_cooley said, it is only available in versions of Windows 7 from Professional to Ultimate, that is, to run XP mode. If you have one of those, you can download from the official Virtual PC page:
http://www.microsoft.com/windows/virtual-pc/
Though, you can still run Microsoft Virtual PC 2007 on any windows machine, by downloading and running the installer from here:
http://www.microsoft.com/downloads/d...displaylang=en
It's OK, you'll notice it's from the Microsoft Download section, so it isn't any kind of crack, or illegal downloading.
Just go to the bottom of the page and download the 64bit installer.
That will install Virtual PC 2007, but NOT XP mode, as that is only available in the versions Pro to Ultimate.
Fire Cat