In answer to the original question - I'd go with whichever platform they use at the university (which is most likely to be PC).
If your wanting to take work home you've been doing in the uni labs and vice versa its a good idea to have the same platform. Whislt maya files in themselves will work on either, there are a lot of plugins (not sure about scripts) for maya and shake that arent available on OSX, and whilst its a very nice operating system, unfortunatly its still yet to be widely accepted as a serious 3D production platform.
I'm guessing this will change over time, but thats how it is right now.