I have a 945gclf and everything works flawlessly (except audio input).
Retail leopard 10.5.6 installed without problems. The hard disk is completely vanilla (I have che chameleon boot loader on an usb stick, with a suitable DSDT which I downloaded and enables QE/CI and resolution changing). Only two kexts must be installed, for audio (output only) and network.
Updated to 10.5.7 directly from software update without any kind of problem.
I have an old IDE hard disk there, but from what I've read, SATA works as well (and evidently faster).