I remember having this problem a few times before, I believe back in Mint 6, and I somehow fixed it there. Mint 7 came with no real issues with the sound and worked perfectly fine. Now on Mint 8 to have a play around, as well as to see how well it runs on my laptop, I have no sounds, at all. I've done everything I could to look for settings that are doing it, but nothing has helped. I'm getting 0 sound through the speakers, and I have no idea how to fix it. I also have a couple other things, but this one is the major one for me at the moment.
I can say that for some applications, it is recognizing the sound card, but PulseAudio doesn't seem to be picking it up at all, and I found no way to even change this anywhere. I can't seem to change it back to the ALSA drivers that worked before. It seems as though PulseAudio isn't detecting my sound card at all for an output device. It's an on-board card, Intel 82801H (ICH8 Family) HD Audio Controller. Everything else though, seems to be working fine.
 I also tried this topic
to no avail.
[edit2] Did a TON of searching, even on the Ubuntu Forums. Apparently Pulse Audio is the issue and not the OS itself. I had to do quite a few things to get it to work with my laptop. Exactly how I did it, is hard to say..