Beware of Vista at the moment. If you're using wireless internet at your university through a VPN client, it won't work on Vista without some serious tweaking.
I don't recommend a MacBook. 1.3 times the price is an understatement. It's roughly 1.5-1.7 times the price for a similar spec'ed machine. I'll find proof if needed
Make sure to check out TabletPCs as people have said. I got a laptop last year for University, and I really regret not looking into those.
As for rough specs...you should look for something along the lines:
12-14inch WXGA screen -> the smaller the size, the lighter the laptop
Core 2 Duo 1.6GHz - 2.0GHz -> anything higher is overkill
1GB RAM -> 1GB should do as you don't game. Get 2GB if it's a good deal.
Integrated Video Card: doesn't really matter what video card you get with it.
Sound Card: something labelled SoundBlaster would most likely do better compared to most onboard sound.