Have you head of "Microsoft Virtual PC 2004", damn this is the kewlest thing i've come across recently, It's even Cooler when I can run a linux box on top of my windows.
Alright here is whats its all about. MVPC 2004 can create virtual pc's as many as you want. and the best thing is it emulates all the hardware as well. Ive been waiting for somthing like this for a long time. You can Install almost any OS in it. you can use it to test stuff. like complicated application, networking stuff. All you need to do it build a virtual pc do your stuff in it crash it, build another and your real PC and applications are safe in the end.
Have a look at Microsoft Virtual PC 2004