I would go with a 2.0 setup for now, and then add a sub down the road. Something like the Infinity P363 would be my recommendation, there is a big thread on them, and they are pretty popular budget speakers. You will still find plenty of bass with towers, and will make your money go much farther. Later on pick up one of the aforementioned subs, and a center channel and go from there.
Denon AVR-1713 | EMP E55Ti | EMP E56Ci | EMP E5Bi | BIC F-12