It's not just architectural differences; Apple goes out of their way to make OS X break on the hardware they don't sell. This is a definite violation of freedom zero.
My understanding was that it's less malevolence on Apple's part than Macs not being quite like PCs architecturally, particularly with respect to firmware -- but it's somewhat orthogonal to both my (strained) analogy and my point. :)
I like both OS X and Apple hardware. But we're living in the future, compared to back when I first got into computing, and data is a lot more easily transportable between platforms. If at some point I decide that I don't like that combination enough to pay the price differential between a new Mac laptop and a comparable PC laptop[1], switching platforms will suck a little, but it won't be a nightmare. I simply don't agree with the assertion that my freedom is cruelly curtailed if I can't run OS X on a cheaper Acer laptop.
[1]: Please nobody tell me that I'm paying three times as much for "exactly the same thing," or conversely argue that Macs are cheaper than PCs if you only look at it the right way. No, I'm not. No, they're not.
