The other poster is right, I believe, that you need the latest nVidia drivers to get sound. And from this thread
http//www.linuxcompatible.org/forums/viewtopic.php?t=187&highlight=a7n8x
one of the most recent posters says that the 3COM driver for that NIC are provided on the CD that comes with the motherboard. Let us all know if this works, as many seem interested in getting this mobo working under linux.
Good luck!