With a Dell machine I can run any of several flavors of Linux for instance, or Windows... and consider that the company that made the machine IS NOT the same company that makes the OS.
Go you one further... look into the hardware that is inside the Apple boxes, and you'll find the same HDD, the same video card, certainly the same Memory and the same Processor, yet if you put in a fancy case with a fruit logo, you can charge twice as much. Ironic eh? If MS tried to do that, no doubt they would be hit with antitrust litigation, yet APPLE can do this with impunity.
For those looking, go find the Microsoft computer... you can't buy one, they don't exist... MS does not put together hardware on which their OS runs... APPLE does. But the computer aspect is NOT where APPLE makes its big profits... nope, the big bucks come from itunes, ipods, iphones, ietc, where they do control all aspects of the market.