If you have the room, I might upgrade the center speaker to an bookshelf speaker rather than a horizontal MTM like the RC3. The subs are pretty good, but you can always have better subs, some 15"s from Hsu or Rythmik would be a substantial upgrade. If it were me, I would replace the side surround speakers with a monopole design, ie bookshelf speakers. You can also get a receiver that can decode object oriented sound tracks like Atmos and DTS:X. I would also get a AVR that has pre-outs so you can use a separate amp in your system, that will help your AVR last longer and give your speakers more headroom. I suppose from that list, I would attack the center channel first and get another style of speaker for the center.
