I had Ubuntu 6.04 and there were many errors about Audio drivers and devices not working. I turned it off and that was it at the time.
Now that I have upgraded to Ubuntu 8.04 (avoiding the bug in October Debug in regard to a huge error in generating an SSL key and all of that!), I thought I'd try again.
I use VLC so I tried to run with that. I could see the audio equalizer so I thought that it should be working and we should hear the audio... but nothing at all. And VLC would spit out an error about the pulse audio deamon not working properly: