your pc audio jacks on back of sound card,out to home theatre reciever...thats if use your dvd-burner or rom drive in pc to watch dvd's...dvd in to hdmi on monitor input to use monitor for viewing,then you would hook up the dvd changer audio out to the reciever audio in
or.......if your sound card has optical audio out......optical audio cable from sound card to optical audio input on reciever,if your monitor doesn't have hdmi then....hdmi from dvd player to hdmi to dvi conveter then dvi connection to monitor,there's a number of ways to hook it up....Or do you just want to hook the pc up to the home theatre for pc sound?
1) 1/8 inch minijack out from onboard or sound card to rca red and white composites on receiver most basic
2) (HDMI output) on video card to (HDMI input) in on receiver with (hdmi out) on receiver to (HDMI in) on monitor if available
or you can use (DVI out) from video card for video on monitor
3) (Toslink output) on sound card to (toslink input) on receiver if available (my favorite)