It doesn't hurt to mention the type of soundcard you're having problems with (we're not psychic
) Just about every soundcard should be autodetected, although the soundblaster live 5.1 cards neet the emu10k1 module added.
That means, at some point after you boot, you go to the command line and type:
modprobe emu10k1
All should be good after that, but that is a typical example. Things seem more difficult with Linux, but it is more illusion than reality.
Oh, and RH9 is a couple years old now. You might save yourself quite a bit of suffering if you tried a newer version of Linux, either fedora (redhat's decendant), or another distribution, but something that has come out in the last year or more recently.