Hi all
I went the following path to upgrade to 10.5.6
:
1. got the 10.5.6 combo upgrade from Apple,
2. made copy of my kexts and good faith
3. Started upgrade, Finished ok.
4. Forgot to remove AppleIntelCPUPowerManagement.kext (or similar - more on that later).
5. On top of that (no reboot yet) I reinstalled Voodoo kernel 9.5.0 + Disabler.kext.
6. Reboot
I never got past the booting screen (grey screen apple logo). 
Went in with single user ( -s ) and removed AppleIntelCPUPowerManagement.kext, the kextcaches, etc and noticed in the "1" script that there is a line "kextload Dont_Steal..." which I modified to read "kextload dsmos.kext".
Machine rebooted into Leopard
, all seemed good but resolution 1024x768. Installed the old Natit.kext and Ati-something-legacy which used to work (no QE/CI) for me. reboot. Now I can see the resolutions from the configuration settings, changed it to proper resolution 1280x1024, worked!. Only problem is that after the "grey apple" loading screen, I get screen corruption, then normal blue apple loading screen. Minor detail.
System profiled and "About this Mac" crashed. Found fix to replace AppleSMBIOS.kext with another one, I got one from somewhere (this was about 1am so I dont remember all detail) and voila! worked.
Current problem: Machine does not reboot properly or shutdown. I have to use reset and power buttons for that. It seems to me an ACPI module issue? maybe the AppleACPI*.kext from 10.5.6 does not work on AMD? Any ideas, proposals, solutions? Should I replace it with something else?
Thanks in advance...