MCSA – Win2k or WinXP Track?

I’ve been the default Sys Admin of the Insurance agency I’ve worked at for teh past 2 years (medium size, 25 user and 2 servers) I would like to switch from being an insurance agent to what I spend most time doing anyways, Sys Admin. I think the MCSA would be perfect for me. I’ve already passed half the A+ (today) and will take the other half Friday. and then try for Server+ in late Dec.

I see there is an option of doing win2k or win xp for mcsa core test. which should I go with? I know not many people are using winXP yet, but eventually they will, and isn’t most of it the same anyway?

any help/direction would be great. Thx