Replying to Mac questions

So I am getting a MacBook Pro very shortly and I was wondering if the 13 in. 2.8 GHz dual core would be fine for general college student work (dont know my major yet) or if the 15 in. 2.2 quad core would be worth the upgrade. Both have the same memory and run at the same rpm's but I guess my main question would be does the quad-core increase the performance enough (even though its opperating with less GHz at 2.2 GHz) or is the 2.8 GHz dual core enough to do what needs doing?