I had gotten an iMac last Christmas. It had OS 9 on it and I had tried to upgrade it to OS X. And guess what happened. By upgrading to OS X, I fried the logic board! :x In my entire life of working with computers, I have never actually damaged the hardware by simply upgrading an OS or performing any software task. Well, I did it on the Mac. Not exactly a good first experience with Macs. The upgrade directions did tell me to upgrade the firmware before installing OS X. I had tried it twice, but it didn't give me any messages. I figured it must've done something. Bad mistake. I was actually able to do the entire OS X install. But after a did some OS X upgrades over the internet, I was never able to power up the Mac again. I pressed the power button and after 2 seconds, it would shut off. So I brought it into a computer repair shop (the first time ever for any computer I've owned). And after several days, they told me the logic board was fried. They said that 1 in 100 people who upgrade to OS X fry their logic board. So, if you are considering upgrading to OS X, make certain that you upgrade your firmware. Otherwise, you risk replacing the entire logic board.