All of these comments miss the point. You bet Apple has a monopoly. Here's the pudding: Apple uses a small range of hardware manufacturers so it has a small range of hardware to support. If you look at that hardware, e.g. video chipsets, processors, ram, it's 100% identical to PC components. Apple designs the case and layout of the motherboard to fit in the case, but that's it. To use your car analogy, Apple is basically taking the internals of a chevy or ford, putting it on a new chassis, and calling it an Apple. As much as I love Apple, Psystar has a good chance to win some parts of the suit.
Why do you think Apple bought a chip company, and why do you think they've been pushing for H264 chips to be in Macs? That's the only way they'll be able to define an Apple computer, i.e. one that has Apple guts. With the move to Intel, they've gotta start adding their own in-house produced chips, or they'll never be able to stop the clones. By adding their own in-house chips and tying it to software in the OS such as Quicktime, Apple would be on much more solid ground.
@icoffee, good point about the hardware, at least for intel macs