I had sound issues in my laptop, the same issues I had with gutsy. (No sound at all)
I ended up manually removing Pulse and all of the alsa and audio modules and recompiling alsa from scratch.
Its a bit of an excessive method to get it working and it completely destroys pulse audio but sound now works perfectly.
I effectively have the same audio setup I had in gutsy.

Out of interest if you boot from the hardy live CD do you get audio?
If you do then it might be a config issue where your previous config has messed up during the upgrade.