Open Firmware is the biggest problem. There was a G4 emulator that was being used to run MacOS on X86, under emulation, but last I heard, it wasn't robust enough to even attempt to run OS4. Same problem with the RISC emu.
My thoughts were you would need at least a core duo at 3.0ghz to make it even bearable to run at a decent speed. I'm not sure if that's entirely accurate, however.
Someone out there, with more technical experience could elaborate more (waiting patiently for Piru or Bloodline). Me, I'd much rather go back to my reading on Quantum Mechanics. ;-)
