Are you an adventurer you likes to try out new things? If your answer is in affirmation then try this out: Install Microsoft's latest operating system, Windows 7, on your existing Vista/XP machine. A tutorial is available at W7forums which teaches you to run Windows 7 by using powerful VirtualBox application. But mind you, it ain't recommended for faint hearted who gets worried each time something goes wrong with their PC. But if you're pretty good with computers then do try it out as it'll give you hands on experience on Windows 7.

"Trying out Windows 7 isn’t quite as difficult as you may think, as you don’t need to wipe or dual boot your existing Vista/XP installation to try out the new Microsoft operating system. It is entirely possible to run Windows 7 from within your existing Windows installation, at the cost of reduced performance. All of this is thanks to virtualisation technologies which allow you to run a computer within a computer."
[Tutorial at W7forums]