Hei

You would seem to be missing at least an
'alias snd-card 0 snd-atiixp' in /etc/modutils/alsa or wherever (I'm not in Knoppix right now)..

did you do alsaconf?

regards

EDIT: Just came across something that may be relevant..

"There's a small trick with the Slackware install I only figured out with some concerted googling. Hotplug automatically loads both the appropriate sound module (snd-atiixp) and another module (snd-atiixp-modem) that causes a conflict, leading to no sound. So disable the modem one in /etc/hotplug/blacklist"