A little googling reveals that sound
should work on your computer. If you check out
http://www.linux-on-laptops.com/dell.html, you'll see a couple of pages for people who've gotten it working, albeit on other Linux distros.
Since I don't have a Dell and don't have sound, I can only make some guesses here.
Firstly, have you considered upgrading to FC5? The web pages I looked at seemed to imply that getting sound working on that model was a relatively recent thing. (Yes, I know that's a pain, but you might want to look into it.)
Alternately, have you tried:
- Installing the updates?
- Making sure you've installed every package with 'alsa' in the name?
- Running 'system-configure-sound'?
Finally, you might try doing a 'modprobe snd' as root. If that doesn't work, find out the audio chipset your laptop uses, find the name of the driver it uses and modprobe that as well, then rerun system-configure-sound.
Sorry I can't be more helpful.