My school uses 2000 pro, even though all the PC's have a XP pro COA number on the side of them. Also Mac OSx for the music department - annoying as hell, as all the mac's are the origanal iMac (CRT ones with coloured backs.) And Tiger in the recording studio.
I mostly see xp home, exlcuding my school, as there are about 400 computers with 2000pro, and about 150 in a room, they put the old computers on. I think they use NT.
Cisco CCNA, Comptia A+, 1/3 through CCNP