Windows 2000 never let me down EVER....i think it run for like over 1 year on my old rig with no errors,no problems at all until i sold it for a new system.
windows 2000 is stable and very similar to windows xp. not so much for gaming though, but then again, any virtual machine is not good for gaming. i use it to test out downloaded apps and such and doesn't require activating every time it is deployed.