You can try VIA's updated drivers here
http://www.viaarena.com/?PageID=88 - you'll have to get the sources and recompile them yourself as no packages have yet been made for Mandrake 9. You'll also have to manually edit the file modules.conf to force the operating system to load VIA's new driver instead of the Mandrake default.
But don't bother.
My motherboard has VT8233 audio, which I tried to use for about a day... The best I got was something vaguely resembling static, even with VIA's updated drivers. Curiously enough, Windows did the same. Save yourself some hardship and get a cheap £15 hardware sound card.