OK, the problem seems to be the VIA sound. But there is a workaround, next to either stripping the music from the pk3 files (which is a bad idea) or installing a PCI sound card:
http://www.accidenta...om_problems.php
Or in short:
1. Make sure you've got aRts installed. You'll soon know if you haven't.
2. Change your quake3 startup script (/usr/local/games/quake3 for me). Where it reads "./quake3.x86 $*" change it to to "artsdsp -m ./quake3.x86 $*"
3. Run 'artsd -F 6 -S 256', and keep it running...
4. Start Quake 3!
I squeezed the arts stuff in the quake3 script too, with a 'killall artsd' in front. In other words, this is my quake3 script:
#!/bin/sh
cd "/opt/quake3"
export LD_LIBRARY_PATH="${LD_LIBRARY_PATH}:"
killall artsd #new
artsd -F 3 -S 256 & #new
exec artsdsp -m ./quake3.x86 "$@" #modified
As you can see, I lowered the value for -F (fragments), because I had the feeling there was some delay in the sound. 3 was the lowest value without crackling sound, but for your setup a higher value may be necessary.
Happy fragging!