You kids and your supercomputers at college these days.
I got through my undergrad years with pencil and paper, and using the 80286/80386 machines at ASU's computer labs... when I could get time on the waiting list. Turbo Pascal FTW.
It was easier about a decade ago for law school. I bought a POS Toshiba Wintel laptop that I didn't expect to see survive the process... and it didn't. It gave up the ghost six months after the bar exam after being rode hard and put away wet for just over three years, and it looked every inch of its ordeal. Not long after that, the Apple Intel changeover happened, and I saw my opportunity finally to switch to a Mac. No regrets.
Now that you've gone and gotten off my lawn like I wanted, I would recommend the MBP because you want to have that extra bit of device connectivity and expandability -- it seems very often in college there are either projects or situations where you need to use your computer in an ad-hoc manner in a way you never expected, and I tend to think that the Air, while a fine machine, will not rise to that challenge based on its inherent minimalism. If you can afford it, an iMac + iPad combo might be even better, because in all reality your portability needs are 95% of the time going to be limited to note-taking, paper preparation (Pages for iOS!) and internet lookup/consumption, and then at home you have a substantially more powerful main workbox in the iMac that is even more versatile than what a MBP can give you, in terms of ad-hoc functionality. The main thing is to expect the unexpected, because that is what is going to happen.
Or you could buy a POS Wintel laptop like I did, use it until you are grinding its rims on the asphalt, and use the money you save to buy the greatest loaded Mac you ever wanted upon graduation. Your call.