What processor???
The problem is that you will be stuck getting the onboard AC'97 Sound. However, you can disable it.
My suggestions are
INTEL CELERON / P4 Platform :-
Gigabyte GA-8VT800 -
S478,800MHz FSB,400DDR,3DIMM,5PCI,AC97,8XAGP,VIAPT800
AMD DURON / ATHLON Platform :-
Gigabyte GA-7VT600 -
Via KT600,8xAGP,ATX,5PCI,DDR400,6USB2,AC97 6Chl.
I really try to emforce it on to end users that it next to impossible to get a mother with out the on board sound.