I am a complete Mac newbie (other than my iPod Touch). I just bought a new iMac from Best Buy and got a great deal on a floor model. Problem is their MAC specialist on the Geek Squad was not there. They tried to reimage the unit but could not. I took it anyway to play with. After installing the OS disc I get a message "Cannot install OSX on this Machine". I did notice that the discs given to me are 10.5.2 OSx and the machine already has 10.5.4. Could this be the issue? Please help me out. I just want to revert it to out of the box status.