Exact same problem here.

P35DS4 1.0 Bios F14
C2D E6750
4 Go DDR2 800
8800gts 320

i am running leopard for almost two years and it works perfectly (currently running 10.5.8 with Chameleon RC2 + custom DSDT.aml for audio + smbios.plist).

But with the SL GM 10A432 No matter what i do, i get KP when running snow leopard after a couple of minutes (sometimes 10-15-30 minutes). I did not had this problem with WDDC release...

* Kext used : dsmos, openhaltrestart, platfor UUID, NullCPUpowermanagement, IOAHCIblockstorageinjector, LegacyHDA (i tried with only dsmos and a DSDT.aml but KP again)

I tried differents things which does not solve the problem
*PC_EFI v9, v10, v10.1 v10.2
*Disabling OC
*Using several custom DSDT (with or without gfx/ethernet/audio)
*Removed some kexts (but I don't think it's a kext issue)...