I would say laptop, a cheap laptop then you might not game on so much and thus get better grades. Just speaking for experience, thats all
I wish i had gone laptop at uni;
DVD's on the train home at weekends.
Doing work in the park/beer garden in summer.
Being able on go home a feel less guilty because you can work there too.
More security as you can take it home for the hols with you.
Taking it into college, jacking into the uni network and using thier uber bandwidth.
Easier in a small flat/uni halls.
Easier to move with (you will probably move about 3 times).
Taking it around you class mates when doing group projects etc.
Yeah, a SFF would be very nice and a good chioce, but from experience I wish i had gone down the laptop route myself. The only thing is the cost.