XP Pro, Fedora 3, and W2k3 Server all running concurrently on the same box. Makes development for different platforms so much easier. A bit heavy on the computer usage but nothing too bad as long as I don't run too many at the same time. I am having some issues with the Linux kernel disagreeing right now but I'll sort it out soon enough. It doesn't take the place of my real linux box or my server but at least I don't risk damaging one while testing something.