For this to be your only computer, you're gonna need
1. enough storage
2. an external disk drive
CDs and DVDs aren't gone yet, you'll find yourself in a situation where you'll need one someday and you'll smack yourself.
Only problem with this, is you might end up having to spend a ton of money. I use my new 2011 13" Air as my main computer, but after getting everything I needed it ended up being almost $2,000. If I would've just got a 13" MacBook Pro it would've costed wayyyyyyyyy less.
Btw, I have the same uses as you. College student, normal duties, nothing extreme.