I just came across Altiris Software Virtualization for xp. It is tremendous, ended up reinstalling my xp setup in parallels because of it. Here's what it does. -get yourself a clean xp install with updates. Install ASV it's free from here http://www.pcmag.com/article2/0,1759,1941829,00.asp you just need to signup, I think there are other downloads elsewhere. once installed, download firefox or pop in office or whatever. open altiris create a new layer, select the installer, and let it run. Altiris will grab all the dll's registry keys etc as it installs. when you are done you can deactivate the layer, and the system doesn't think it's even there. activate it and it's available instantly. Anything you do in the program will stick with it. Coolest thing, although I haven't tried it yet, is that you can take an installed apps files and port them to another machine without having to install. it's worth checking out. I am blown away.
