I walked into an Apple Store last week deadset on buying the fully loaded 15" MBP... Quad core Intel Core i7, and all the goodies. The guy at the Apple Store told me unless I'm majoring in communications or film, that 15" is useless. Waste of money, but also the i7 eats battery life and makes the aluminum extremely hot.
I'm on the 13" now, with the Core i5, 4 gb of DDR3 RAM and 500 gb hard drive space all for $1099 (student discount holla). Well worth it. The MBA is expensive for no CPU power. If you're planning on running Mail, Safari, MS Word, MS Powerpoint, iTunes, and iChat at the same time -- which seems like the norm for any student -- the MBA will not fit your needs. Yeah, it can fit in a manila envelope, but get the MBP. It's light, more powerful and cheap(er).