I'm surprised that Knoppix is still around, honestly.  In any case, most
audio cards are supported in the 2.6 kernels using the ALSA drivers.  If
the resource websites for Fedora don't help you out with debugging the
audio card, give the ALSA website and resources a try.  The `alsaconf'
application should get you started.  Also try to use the `alsamixer'
application.  I've found that occasionally the only thing that needs to
happen is to get the mixer behaving correctly.

There is also some weird interaction between the old sound API and
drivers (OSS) and ALSA.  Download and install the `aumix' application.
Crank the mixer volumes all the way up for this OSS driver-based
application, then use the desktop-integrated ALSA mixer to fine-tune.

Audio is not fun, but once it is working, it works well.

Good luck.

Chad