Congratulations on the new stuff!
The center is awfully high up, would it be possible to bring it down just under the tv? You would get a better localized sound from it.
For more "impact", you need sub (or subs!) my friend.
I picked up that same model Onkyo from Best Buy as a closeout to re-sell, but before I sold it, I tried it out in my theater, just to get a feel for it. I just ran a quick set-up with the Audyssey mic and let it run DTS HD-Master from the bluray. Sounded good, even compared to my Elite.