2000 gives you freedom from that tiresome product activation, while XP gives you limited game compatibility and some mostly useless extra features wrapped up in a prettier but skin deep interface. Err, I run win2k, and I can assure you that it has "limited game compatibility" all by itself ;)
It's not too bad, really, but I thought the point of XP was that the game compatibility was supposed to be somewhat less limited....
The way I thought of it was that 2000 had
no game compatibility, and XP improved that to "limited".
Hope that helps.
D