[CentOS] Microphone problems with Skype

Hi,

I have CentOS4 and this soundcard:
00:11.5 Multimedia audio controller: VIA Technologies, Inc.
VT8233/A/8235/8237 AC97 Audio Controller (rev 60)

I installed the Skype rpm for Fedora3 and it works but the quality of
my voice is very poor: volume is low and the voice sound doesn't have
the high frequencies.

Did any of you made Skype work perfectly under CentOS4? How?

Thanks,
Adrian