http://www.linux-tested.com/results/asus_k8v-x.html shows the results for Red Hat 9 with the Asus K8V-X motherboard (the one that I have; yours is not listed). For audio, it says: "Audio chipset not supported in Linux and no drivers available." Roughly speaking that translates to the hardware manufacturers not supporting linux like they should. They write plenty of software drivers for windows, it would only seem fair to do the same for linux.
I see 2 possible solutions for you:
(1) disable the built-in sound on your motherboard and use an add-on sound card that is supported by the linux you have.
(2) get a newer linux distribution that can use the built-in sound card on your motherboard. When looking for your new linux distribution, you might want to go to
http://www.linux-tested.com to verify that your new distribution will work with the sound card on your motherboard.