If my PC goes tits up then I'm very comfortable digging around in the registry and all the fiddly bits to sort it out. If my Mac ever did the same I wouldn't have a clue where to start as the entire file structure and program is completely different. I'm not saying that it's any more difficult to learn as I suspect it's not, it's just what I've grown up with and what I'm used to.
For me, a PC makes the simple things more complicated than they need to be at time, whereas on a Mac the complicated stuff becomes an absolute impossibility to sort out. That's the real downsides to both units, although Win7 is about as perfect an OS as I've ever used and makes the call for OSX much less urgent. Still needs tidying up though.