Thanks for this brilliant guide. I managed to get 10.5.4 running on my previous motherboard four years ago, but that machine bit the dust last year and I've just gotten around to attempting a Snow Leopard install this weekend. Thanks to this guide, I've got 10.6.3 running on the following hardware:
Busratio=22 was the key to success, it seems. The wireless card is Mac compatible, so I've got net access, HD audio, but no graphics acceleration yet. I'm getting the impression that HD 6550D GFX support is limited / experimental, but I'm slowly getting reacquinted with all the KEXT editing stuff I've forgotten about over the past couple of years. It would be nice if I could get the graphics card working, since everything else is working a treat.