Hackintosh Update
After a week of different installs and frustrations, I finally got my Hackintosh upgraded to 10.5.7 with Quartz Extreme (QE) working. My graphics card is a Nvidia GeForce 8400GS with 256MB.
Essentially I followed the instructions below to upgrade to 10.5.7. I then added the appropriate EFI string using OSx86 Tools, removed NVinject and NVEnabler 0.1 kexts, repaired permissions, and cleared the extensions cache. When I rebooted, everything was working (finally)!