I was a bit lazy to read the other comments, so I'm sorry if I'm repeating what someone has said already.
It all depends on what you need portability wise.
If you want the best of both worlds, get the 15" 2.4 or 2.66 MBP, as 15" is probably the maximum size you want to take for school, and the gaming performance is pretty awesome for such a laptop.
If you don't need the portability, an iMac would probably be best, as if I'm not mistaken, they are cheaper.
Now if you don't need the best performance out of your games, the alu 2.4 MacBook might be enough and much more portable than a Pro.