While soundcards are up for discussion. Here is a tip I discovered last week 
which someone might find useful:

I discovered that in order to turn on the microphone on machines which have a 
Creative Labs SoundBlaster Audigy card and are running SL 4, use alsamixer and 
turn on mic capture, do NOT use kmix as it turns if off again!

Fabien Wernli wrote:
> On Tue, Jul 26, 2005 at 02:13:02PM -0500, Vaibhav Vaidya wrote:
> 
>>The sound in X doesnt get enabled until I go to sound card detection and
>>play test sound...
>>[...]
>>and test sound) can play concurrently and appear as mixed sound. But in
>>linux, unless I stop a song, other sounds (say yahoo messenger message
>>[...]
> 
> 
> Not sure it's already there by default, but if not, install alsa, then run
> alsactl as root. In XMMS use alsa output plugin.


-- 
  Alex Finch, Research Fellow, Physics Department, Lancaster University.