Sound Card Problem? Please help

I have a sound Blaster Live Value card. From the audio out, I have a headphone, to Stereo(red/white) plug runniong from my computer to my steareo surround sound reciever. Whenever I play an avi, all of the sound comes out of all five of my speakers(even if the AVI is encoded in dolby digital stereo). I am looking aty a nw sound card with an optical output. If I do this and plug it form the optical output to my optical input on the reciever, will I get better sound from my computer going to the reciever?

I think I am getting this problem because it is being split from a headphone to RCA?

Any help would be great.


One last thing to note, the sound out of my DVD player(which is connected to RCA to me recoever) plays things perfect.
I am playing MKV files through Media Player Classic. If that heeelps to narrow down my solution. So basically what I am trying to do is make my MKV files played from media player classic sound like A true DVD(the MKV files are ripped directly from DVD's so the audio decoding should be the same.) I am in dire need of help

Thanks again.
Zero