I've been reading thru some of the other messages here and I'm still a bit confused about how to best connect everything in my specific situation.

First, I think I just learned (after using these for 4 years) that the red/white RCA audio cables going from my Cable box to my HT receiver are NOT carrying 5.1 surround sound like I thought they were. Is this really true?

If true, then I need confirmation that what I'm about to do to reconfigure things - and add a newer, upscaling external DVD player to my 4-year old existing HT receiver (which already has a built-in DVD player) will work properly.

My existing HT system (Panasonic HT900) does not support HDMI. It does have "Optical In"

My new TV (Panasonic TH42PX80U) is only 720p and it does have HDMI inputs as well as "Digital Audio Out" and the manual states to use "Optical Digital Audio" cable for this port.

So, is "Optical In" on the HT the same as "Digital Audio Out" on the TV? Because of how things are set up in the wall unit it's very difficult for me to get back there to check - it's definitely a 2-person job to get back there. I'd like to confirm before buying the cables.

I'm currently using Component video from the Cable box to the TV and RCA audio L/R from the cable box to the HT receiver. DVDs play directly from the DVD player that's integrated into the HT receiver. But, the integrated DVD player does not upscale.

My plan is to buy some HDMI cables and an optical audio cable; use HDMI from the cable box to the TV and HDMI from a new upscaling DVD player to the TV; then use optical digital audio cable from the TV out to the HT receiver. Would this arrangement send 5.1 surround from both the cable box and the external DVD player to the HT receiver?

Am I wasting my time getting an upscaling DVD player to watch on an 720p TV? I'm hoping that I'll see a difference between the native 480p DVD and the upscaled version even if it's only 720p. I'm interested to hear real-world experiences with this.

thanks!

In your situation, connecting optical is the best way to get 5.1 from your equipment. Connect your audio directly to the receiver, NOT the TV. Most TV's will only pass Dolby Digital from the interal ATSC tuner. All other inputs will be downmixed to Stereo.

As for upscaling, you may or may not see a difference. It really depends on the scaler in your TV vs. the scaler in your player. Most of the time the player will be better.