Well, congratulations to everyone who doesn't have sound issues. That doesn't really help those of us who do. I did Google before selecting this MB/CPU and found people saying they had no problems with it. That's not my experience, so don't flame me like this is my fault. I've been working on this for 2 weeks now and finally found one (ONE) distro that worked: Ubuntu 11.10. Sadly, since multiple people in this household use this computer (or will, if I ever get it working), I discovered a (common) problem with that distro: it often locks up fast-switching users. But, hey, isn't that LightDM cool? So what if it locks up?
If Ubuntu can properly use all my hardware out of the box, why can no other distro?
It's ridiculous: buying mainstream popular hardware, then adding a current OS to it, and I can't even play a damn CD or watch a movie! I love Linux--been using it for over two years--but sometimes you need an MS in computer science to do something as simple as listen to music or watch YouTube. Clearly, it's still an OS for hobbyists who love getting daily kernel updates, recompiling their own software, and tinkering with configuration files.
FWIW, I put my decade-old copy of XP on a 2nd partition: everything worked out of the box (after installing the drivers): video, sound, flash--even sound through my HDMI.
If I can't finally get this resolved, I'm steeling myself to get Windows 7. But first maybe I'll try adding a separate audio card as Murdoch suggested above. (As I said--ridiculous.)