I have a Samonsite backpack I got at at Fry's in Calif. It's pretty nice. Seperate laptop enclosure, two main pouches and a ton of ancillary ones.
Also, try to avoid Targus, that screams "LAPTOP INSIDE" and theives know it. Try something a bit more discreet.
I take it with me when I travel now and used it for a year in college. Still looks new.