I think your audio troubles are feedback. I amsure you did, did you plug the wire into the sound card mic or the sound in port ?
I also have the chris video capture, I too have a video capture card and a tv card w/ vid capture. The plain video capture card I have is the conexant chip set and i bought it new for around $10.
I had a " motor boat " type sound that I fixed in software, do not remeber what, it was eather windos configuring , double click the speaker icon in the icon tray , then clicking options , then properties, the radio button for recording, maybe playback, uncheckin / checking different items, or in the vid capture program
selecting the imputs.??? do not remeber