Throw a bulk of your money toward the speakers.

No need for newer AVR since your gonna be using a PS3 (it decodes the new audio formats and outputs the signal over HDMI v1.1 or up), I'm assuming for BR playback. Something like a Yamaha 661 from Best Buy will do fine. Doesn't have the latest HD audio decoding but it does have preouts.

If you go with the Onkyo, I would suggest the 705, which has preouts. It offers some more flexibility that may be useful down the road.