My suggestion then is to do your research. I guess I was wrong about all the 2600 series having the HDMI audio feature, which is really weird because the 2600 series has audio processing on the card. I find it a little disturbing that gigabyte can get away with calling that card a 2600XT without all of the advertised features working out of the box. I have this
card in my HTPC. Well, i have a GDDR3 version, they cut it back to GDDR2 for costs and it has great sound on it.
First if your wanting to go through a sound system, the system needs to support HDMI IN, which is very uncommon and mainly found on high end receivers/theaters that are like $500+ so the other alternative is to plug it directly into the TV and use either those speakers or something you have connected via component or something like that. I would say, it's better to have optical out through your sound card where you can get better sound to your audio system and it's a lot cheaper.
I'll agree with you here dragon, thats what i eventually did. but $500 is not a high end receiver, it is more like upper low end. I have a Sony STR-DG910 that has hdmi in and can be found for under $400. Also almost all new receivers and tvs come with hdmi so it isn't as big of a deal anymore.