[CentOS] Centos4 audio problem

Hi,

I am running centos4u5 on dell precision m4300 laptop. I installed vlc player and i am able to watch the videos,but i am not able to hear audio.when i do system-config-soundcard i am getting the below error.

system-config-soundcard Wrong card index 0... ALSA lib pcm_hw.c:1207:(_snd_pcm_hw_open) Invalid value for card aplay: main:550: audio open error: No such device

My installed kernel and alsa rpm are

uname -a Linux demo.xxx.com 2.6.9-55.ELsmp #1 SMP Fri Apr 20 17:03:35 EDT 2007 i686 i686 i386 GNU/Linux

rpm -qa |grep alsa alsa-driver-1.0.15-63.el4 alsa-lib-1.0.15-33.el4 alsa-lib-devel-1.0.15-33.el4 alsa-utils-1.0.13-22.el4.at

Kindly tell me how to troubleshoot and make audio up and running on my centos box.