I agree with the other posters. . .check with your IT people.
That said, assuming it will be compatible with everything (and it likely will be), get a mac. Seriously. I did (got a 12" G4 iBook), and it's been nothing but wonderful. I've never needed the IT guys except to ask them if a mac would be compatible with everything my school used (obviously, it was). My friends with PCs make fairly regular visits to the IT people when their computers go on the fritz.
You won't need a lot of processing power in all likelihood (like the other post in this forum asking if a duo core processor is necessary. . .hah!), but you might want to consider getting a RAM upgrade; 1 gig at minimum. I've found that with anything less, my computer is painfully slow when I load up the 100 slide (all large images) powerpoint files that my profs create.
Bottom line? Get something reliable and reasonably priced. You'll be fine.