If you are plugging the audio into where the dvd player went you are doing it wrong. The inputs on the back are almost certainly numbered, Video 1, Video 2, ect.
You absolutely have to plug in the audio into the same number that the video is plugged into, they likely even have a box around them showing that the audio belongs to that number video. If you don't do it that way, then you'll get audio and video on seperate Video settings on the TV. For example you could get audio on Video 1, but no picture. Or picture on another input but no audio.
There is no special combo to get your audio out, you need to unplug your current speakers (or get a splitter) and plug your audio line into that. There isn't a secondary audio out.
Take a picture of the back of your tv and post here if you can, I tried to find a picture online and didn't find one. I think you are simply not putting the audio and video on the same input for the tv.
Edit: Found a picture of what I believe to be the back panel of the samsung 46", yours should be similar.
As you can sort of see the PC/VGA input which I assume you are using, has a line in right next to it. Its the standard 3.5mm mini jack I referenced in post #3
SNGX1275 said:
On the TV there will be a line in, it very well could be a regular 3.5mm mini-jack just like on your sound card. Thats how it is on my 46" Bravia.
If for some reason you are running DVI->HDMI to your tv, it looks like you need to plug it into HDMI 1 and then the audio into the red and white RCA inputs that are labled "(DVI IN HDMI 1)", if you aren't using DVI->HDMI then don't worry about that.