Onkyo,Denon,or Yamaha for DolbyDigital?

All three of those brands are known as some of the better sounding in home theater gear. Check out Stereo Review. They seem to favor the Denon's for sound quality. You can also see some good reviews on etown.com, audioreview.com, and amazon.com. The etown reviews are a little rosy.

I recently sold my Yamaha DSP-A1 to buy the Denon AVR-5700. Being such similar products I needed a good reason for doing this. Simple answer: The Denon is way more involving in 5.1 and better in stereo. It also has a tuner that is superb. Don't hesitate, buy the Denon AVR-3300. It is a great deal in your price range . In most rooms you don't need as much wattage as the 5700 has anyway.Good luck.

ps. Now I know why they call it Home Theater and not very good television sound!

Denon the best hands down winner in this price range. Only receiver with component switching, 2 speaker set-ups for dipoles or rear surround! The 4800thx even has EX for 3rd speaker in rear surround. All depends on size of your room! Most importantly get best interconnects that you can afford!