I am alos a MAC user and i JUST got maya 2010 bundle that comes with 3dsmax, motion builder, XSI, ect. It runs great so far. I run on a standard issues 2.4 dual core imac with 4gb of ram. I am working on getting my mayatomr issue fixed but if you need or want to play with 3dsmax or XSI use bootcamp on your mac. you can pick up 64-bit version of the os for like $15 if your school is on the Microsoft academic alliance. I got Win XP Pro 64-bit and it makes life really easy. Bootcamp is as easy to use as making toast.

The reason PC are used more is because dell and xp workstation for most schools come with prosumer development video cards like FireGL and Quadro. However I have found mac to be a big help when rendering big projects. I can crank out a 4 day render and not have to worry about memory leaks and crashing that
i have experienced with windows.