I'm unsure of exactly what you are trying to do. I get the impression it is one of the following
-you want to hook your computer up to your tv so your tv is essentially a monitor. If it's this one then are you trying to get the sound to come out of both the tv and pc speakers at the same time?
-You already have a video source for your tv but want to send the sound to your pc which will then play the sound over its speakers.
Am I close?