Looks like your mobo will use an azalia audio kext. That's good because it is quite common. So just go here: http://www.kexts.com/cat/8-audio.html and look through the pages for an azalia audio kext for 10.6.4 or 10.6.5.
For Ethernet go here: http://www.kexts.com/view/204-nforce...ollection.html download it and also go find kexthelper if you have not already. It makes installing kexts very easy. You just drag the kext to kexthelper window and click the button that says "easy installation". After you install your kexts run disc utility and restart. That's it! Hope this works for you.