If anyone is interested.... the issue was missing FakeSMC kexts in /Extra/Extensions folder on the hard drive. Just copied the whole folder over from the USB and it's working.
I have Windows 7 installed on hard drive 1 (MBR) and Mac on hard drive 2 (GUID). Does it matter which drive I put the bootloader on? I can always change the BIOS to boot from a specific drive if it needs to boot from the GUID drive.
Thanks for that. I followed the instructions and I have ATIRadeonx2000.kext and ATI4500Controller.kext loaded using Kext Helper. All the correct Dev and Vend IDs exist in the 2000 kext. However, it's still not working.
The PC won't boot with GraphicsEnabler set to yes and gets stuck almost at the last point in the boot process.
I've seen a few references on the web that this card isn't supported but it should surely work. I am not using any custom DSDT or SMBIOS files - everything is original from Apple Store. The installation USB was created using Uni Beast so maybe it replaced some files? Not sure...
Any more tips? Or maybe I should just get a graphics card which I know will work with my system? I am not using ATIConfig as I am not sure which one to use. The family is RV710 for my GPU but it's not listed in the Chameleon drop down list.