Thanks for all the info guys, I'm getting a much better handle on things now... While I DO have a very large, very high quality digital music collection, at this time my goals for the HTPC build are primarily geared towards watching movies. I could see SOMEDAY adding a high-end sound card/dedicated DAC for 2.0 music listening, but due to budget constraints, that day isn't today. ;-) That being the case, I'm planning on going with a Radeon HD 5750 video card that will pass the digital audio signal (up to 7.1 with TrueHD or DTS-HD MA) to my receiver via HDMI.
Now, two related questions:
1) When I do someday add that high-end Lynx sound card to my HTPC, is there a way to automatically send 2.0 content through the sound card, and 5.1/7.1 content through the video card? If not I suppose the alternative would be manually switching which audio device the computer is using, which isn't difficult, but it would be nice if that step could be omitted.
2) Are there any AV receivers out there that have a good quality DAC built in? It seems like it would be really cool if one box could have both an analog and digital circuit: analog for 2.0 content, and digital for all that crazy 7.1 processing...
Again, thanks very much for all the info guys! It's been very helpful...