I have never seen the airport-style bags that ThinMan is talking about. Most people have messenger bags (I prefer these) or backpacks. There isn't usually that much to carry at once since you don't need textbooks for class in most cases.
just get a normal backpack, preferably one with a laptop thing in it. it doesnt necessairly have to be that big because depending on how your schedule works out youll be able to go back to your room between classes.