I found my fix without changing pulseaudio configuration (which works fine otherwise)
try launching etqw as such:
> etqw.x86 +set s_driver oss
UPDATE(6/11/2010): on Ubuntu 10.10 the kernel is shipped without OSS support. So unless you are going to compile your own kernel, I suggest you to avoid updating. Good work, Ubuntu, we had 2 professional games on Ubuntu (ETQW &RTCW) and you just screwed them all.