You will want your books most likely, but you can get your books unbound (they take the pages out of the binding, then they punch holes into the pages, you keep the book in a large three ring binder at home, and you transport the necessary pages to class in a smaller three hole binder).
There is always the wheelie bag option, but I wouldn't recommend it. Get a good bookbag with two straps and a fair amount of cushioning (I love Jansport's airlift straps, others get North Face, LL Bean, etc.). A friend who used the wheelie bag option actually had worse back damage, apparently the twisting of the spine and the positioning of the bag really messes with your spinal alignment and puts a lot of stress on your neck. (She actually is in physical therapy post 1L year.)
I didn't have my books unbound, I used a two-strap bookbag, and my back was fine following the initial adjustment period (the first 2 weeks when your shoulders will hurt).