There may be a little trial and error, but the Aver card works great. I used it at home for a long time.
You need to try:
1) Picking the right audio output device (the Surround Sound article linked above discusses this)
2) Picking a working audio decoder (in TV device options, again described in the Surround Sound article)
These are the only two parts to television audio so if you have them right, I think you'll get sound.
It'd be best if the program could automatically choose working filters for you, but the world of Directshow filters is not a simple one. If you're on Vista and using an outboard amplifier, I'd recommend the Microsoft decoder filters. If you're using computer speakers, you'll probably want ffdshow as the audio decoder.