I have been following this guide: http://www.insanelymac.com/forum/index.php?showtopic=181293 but couldn't get the audio to work at all on 10.6.3. So I tried instead to use the latest VoodooHDA kext (2.5.6). After it was installed and I ran pfix (I also installed the pref panel), I rebooted. I had sound, but it was very distorted. I can somewhat fix it by lowering the format frequency in the Apple Midi Setup, but apparently I can get it to go low enough (it only goes down to 44.1MHz.) Is there any thing else I can do to alleviate this problem completely?

Try new version VoodooHDA 0.2.6.

much better. Still the occasional bit of static but a great improvement...