Yeah, and even the sound card method you need to make sure that you have the proper header and cable to connect to the graphics input.
It's still a good idea to add it, since it wasn't there before, but unfortunately we get stuck with these situations.
It would be nice if someone like Auzentech had a card similar to the HomeTheatre in a PCI version (don't think it would be half-height though).
You can look for an audio card with an electrical SPDIF output, which are a little rare in findint the appropriate jack to jack for the graphics card input, but for now you might need to connect the strereo out to either a line-in on your TV or a seperate speaker setup. Kinda sucks, I know.