This was a far more informed posting than mine. Correct, I'm running
64-bit FC6 perfectly with on-board sound. However Mauriat has reminded
me that I am running 32-bit Firefox so that is the main issue it seems
for people. Xine/mplayer/vlc though have not let me down..
I'm not saying which version to use, but most likely your sound
will
be fixed by either (manually) upgrading ALSA or the kernel. However it
probably is more practical to upgrade Fedora as mentioned. But there's
always a chance that even an updated FC6 may have sound card issues.
An added note. If you are interested in multimedia, 64-bit linux does
have some limitations. Certain things like web browser plugins and
using some 32-bit windows codecs may require some extra work to setup.