I have a G4 iBook that came with Tiger. I recently bought Leopard under the impression that my G4 met the requirements. Technically, it does but I wasn't able to install Leopard (even with a RAM upgrade). The geniuses at the genius bar at the local apple store all admitted to me that Leopard, even if I could get it to install, would never run well on my G4. And, word to the wise, ever since the installation of Leopard failed, my G4 hasn't worked. In fact, the hard drive is now kaput & I can't help suspecting the failed Leopard installation as playing some role in that (never had ANY problems WHATSOEVER w/ my G4 before that). So, though I'm no expert, from my experience, I would say no, don't do it.