I've heard about "virtualization" for years, but I never thought it was anything I needed to worry about.  I just thought it was something for network engineers to tinker with in big, expensive data centers.  It turns out there are plenty of handy uses for virtualization, using Microsoft's Virtual PC, in your everyday computing life.

For example, if you want to test the latest build of your software installation package, you can fire up a Virtual PC and run your installer on it.  If it breaks, you simply rollback the hard drive changes and you're back to a fresh hard drive.  You can test on any version of Windows without having to setup any hardware.  It's way simpler and faster and cooler than keeping a spare dinosaur computer around with Norton Ghost images.

Perhaps you have to work in a restrictive network where you don't have access to any other computers for testing.  Fire up a Virtual PC and create whatever test environment you want.  You can connect it to the network or not, depending on your needs.  If you break something, you can roll it back to the starting point in seconds.

Or maybe you want to try out some shareware programs but you're not sure if they'll install a bunch of spyware or adware.  (You know as well as I do that once you install Windows software, you usually can't get rid of it without reformatting.)  So fire up a Virtual PC and install it there first.  The virtual environment is completely isolated, so there's no danger of getting any infections if the software's bad.  You can try it out for a while to see if you like it before committing it to your main workstation.

How's it work?  I have no idea.  I can only assume it's "emulating" a PC, in the same way that people have always been writing emulators for older computer systems.  Normally emulators require considerably faster hardware for the emulation to run at a normal speed.  Virtual PC, however, somehow manages to run well even on the same hardware.  It's noticeably slower, of course, but certainly not unusable.  It's about like running an RDP session over a slow connection.

So go ahead and download Virtual PC 2007.  It's even free.