I thought I'd share this, it may help, the sound is now working properly on both my systems.
I have 2 comnputers, both were running Mint4 which I reinstalled to Mint5 the day after it was released....
1 - my laptop (Toshiba L30-10V) already had sound problems and this didn't change after the reinstall, I could get the speakers or headphones working (but not both at the same time) by adding and changing options snd-hda-intel statements to alsa-base
2 - my desktop (Asus Pundit P1-AH2) was working fine until I installed Mint5, things sounded horrible and it wouldn't save my CD volume setting which my TV card is plugged into, so I tried different options snd-hda-intel statements in alsa-base but nothing seemed to work properly.
So off to the Ubuntu forum, lots of stuff about things I had already tried then I discovered an article about there being problems with the snd-hda-intel alsa module which lots of cards seem to use. Some people reckon that problems are caused by the Alsa-base being 1.0.16 while the rest of Alsa is 1.0.15. Apparenlty some sound issues are fixed in 2.6.24-17 kernel but Mint5 is 2.6.24-16.
So it's all a horrible mess, then I came accross an entry which mentioned updating the Alsa drivers, so I did, which was quite easy and now both my computers are working properly, actully better than they ever have before, when headphones are plugged in the speakers cut out (hurrah) but I have not yet tested line-in or microphones. Both my computers use the Realtek ALC861 chipset but obviously different makes and models.
This may not work for you and if it doesn't then I do not know how to back it out, so beware (you may have to reinstall if it screws up)
Here is what i did... (I tried sudo but it failed so logged on as root and it worked).
apt-get install module-assistant
module-assistant a-i alsa-source
... then reboot
Open volume control and check the devices, I found a new 0: device with the correct name, ensure that none of the sliders are muted or at zero.
Hope this helps
BTW I am not sure if this affects PulseAudio (no idea how it works anyway) but as far as I am concerned if my sound is working properly then I don't care