Ok I have my hdtv setup where I have the Comcast HD box going to the Samsung 47" LCD tv with HDMI, then I have the 1000w 5.1 LG reciever/dvd upconverter hooked up optical from the tv to the reciever and hdmi from the reciever to the TV. The Problem is that the reciever will only output 5.1 when playing a dvd or cd from the player itself but not when watching tv.

This is a sketch of my home theater setup.
http://img137.imageshack.us/img137/348/tvlayoutxy9.jpg
Any suggestions will be helpful.

The TV is probably downmixing 5.1 to stereo before sending it to the receiver. AFAIK, there's no setting to adjust to make it do otherwise.

Your best bet is routing directly from the Comcast box to the LG.

Why not connect the Comcast box to the LG with HDMI and let the LG handle all the switching? You should be able to delete the non-HDMI cables.