My experience with 10.6.8:
Foolishly installed combo update from 10.6.7 without consulting tonymac forums. KP before update finished. Restarted with Finder unresponsive. Installed via terminal. System booted no KP. GREAT JOB.....but upon another reboot the dreaded PCI CONFIGURATION BEGIN arose.
Possible work arounds attempted:
all relevant possible boot flags....npci=xxxxxx....DSDT=no.....etc.
using iboot
using iboot to access install disk to access terminal to manually install Family fix kexts.
swapping graphics cards.
attempting to boot with no graphics card.
safe mode.
Accessing Mac partition through windows side to manually transfer kexts.
and so on.
What finally worked for me:
I had to freshly reinstall OSX using Gordo's guide. (thanks man, great guide) I only lost 500 GB of media...no big deal.
Now I will ALWAYS ALWAYS ALWAYS back my data up. It really is the golden rule....
I recommend: Save yourself the time and frustraton and simply reinstall osx. Hopefully, you backed up your data. Read 10.6.8 THE OFFICIAL THREAD, Tonys first post. Read any guide that suits your build. make sure you install the family fix and the new graphics drivers. use newest versions of multibeast and iboot.
Its as simple as that!