I have had my 20" iMac since for about two months now. This past Friday I installed Leopard. I guess I'm just lucky, but I'm not having all of the problems I'm reading about here. One of my co-workers has a new IMac and he hasn't had any issues either. The occasional issue that I have experienced is my system suddenly shutting down. Some of the threads indicate this may be an issue with the additional memory I've installed.