Thought I'd post some useful information for you guys, in case some of you are having troubles.
A lot of people seem to be running into problems running the Test Sound option in the Soundcard Detection Utility. I think this is due to the fact that when you log in as yourself, and the utility wants to run itself as root, the sound card is already in use by you.
A simple command you can try to see if your sound is working ok is to open up a terminal window, or use the "Run Application" option on the "Start" menu, and type 'aplay /usr/share/sounds/generic.wav', without the quotes of course, you may find that your sound is fine.
If that doesn't show any results, check your volumes.. a lot of people have also been finding that ALSA is setting their volumes to 0. Both Gnome and KDE have mixers, and my suggestion is to use them, and check your sound.
If you're using an older ISA sound card, and it isn't detected by the system automatically, the suggestion from most, has been to upgrade to a newer PCI sound card. Most sound cards are pretty cheap now a days. www.pricewatch.com
is a great place to start. NewEgg is also a good, well known, and trusted place to buy from, if you're not into the 'buying from anyone with the best price' type of thing.
The last thing that I've found is a problem, but have not yet found a solution for is.. multiple applications using the sound card at the same time. Say you have XMMS running, and Kopete, if you're playing a song with XMMS, Kopete will not be able to play any sound, like a message notification sound, or whatever.
My theory is this is related to ALSA, as OSS never had this problem for me. Only one application at a time can use the sound system, and it doesn't do any sort of multitasking, or switching. If it isn't ALSA, someone please feel free to post what it is. I just know it wasn't a problem with OSS (Open Sound System), at least for me.
Anyway, I just wanted to throw those out for you guys, so there's a somewhat general location of solutions to the most common sound problems.