HD sound question

I own a mitsubishi 65 in rear projection hdtv with dvi connection(1080i). My surround sound is sent thru a KEF two speaker system with a woofer. I have a comcast hd dvr and a PS3 blu ray player. Right now I use optical cable for audio on the PS3 and the Comcast box. What is audio 3.1, 5.1, 7.1. What can I do to maximize the sound factor? Realistically, the two speaker system fits my living room dimensions the best. I notice on nbc hd shows, i end up having to up the volume and then lower it on analog for the same channel. During football games, sometimes I hear the game great but commentators are low volume. It just seems out of proportion. What sound setup will best take advantage of my equipment or what minimal upgrade will be worth it?

did you get an answer to your question. I am having the same problem withNBC

Whatever you are getting, be it 3.1 5.1 or 7.1 you are missing the MOST crucial component of surround, the CENTER CHANNEL. Without it, the dialog is mixed between the right and left speakers and becomes muddied. Using a surround receiver even only at 3.1 (that is having a center speaker connected) would improve your sound dramatically.

Recently I have noticed that some TV's will allow you to use their speakers as the center channel. If your TV has this feature you may be in luck. If not you really do need a surround receiver (even an inexpensive HTIB would sound better) with a center channel connected and working.