I am entering my 4th year. I used an ultra-portable (12" Thinkpad) for the first 3, and it worked very well. It broke, and I replaced it with a 15.4" Dell (monstrous by comparison), but I don't ever plan on bringing that one to class.
Whether you want to get an ultra portable or not depends on a lot of things. I brought my desktop to school, so I only intended for my laptop to word process, access internet, and maybe watch a few movies or play a few games of Starcraft. Hence, the lack of video power in ultraportables wasn't really a concern for me, while the size advantage was a major concern, so I picked the ultraportable.
Some things you might want to ask yourself:
1.) Is this going to be your only computer on campus? If this is the case, and you know you like playing FPSs or whatever, then that will factor in: smaller laptops do not ship with fast graphics cards. And unless you look at some non-mainstream makers, like ASUS, you're most likely not going to find discrete graphics on anything smaller than 13".
2.) What major are you going into? If you're going to be taking a lot of humanities classes, where notes are mostly in English, then taking notes by typing on your laptop is far more convenient than writing it all out. On the other hand, if you are a science or engineering student, a non-tablet laptop is going to be practically useless as a note-taking device (unless you're super fast at latex or something), just stick to notebook and pencil.
3.) Smaller laptops fit better in confined places, like lab desks.
Regardless, if you are going to be lugging your laptop around a lot, I really wouldn't recommend anything over 15.4"/6lbs, in my opinion, 12"-14" is ideal. If you really need larger screen, buy an external.