I'll tell you, I spent a metric assload on a laptop system last summer, which I quicly discovered was waaay too big and heavy for my midget self. I ended up using this
instead (which someone had given me for free.) I'm not going to win any style awards, but it fits everything and hasn't destroyed my back yet.
I'm also a Timbuk2 afficionado and have several of their messenger bags, but the weight of the books was too much to get away with a messenger-style bag for long.