What the OP and others seem to fail to realize is that when you buy an Apple Macintosh computer -along with the copy of OS X installed- you own the hardware and only have a license to use the software -and that is restricted by the terms of the license to only Apple hardware. Nothing prevents you from running another OS on the hardware that you own. When you purchase a retail version of OS X, you are bound by the license terms to run OS X only on Apple hardware. To run it on any other hardware is in violation of the terms of that license. How is that in any way anti-competitive?