On and off over the past 10 years or so I've done a lot of work with MAC systems up to and including OSX. [EDIT: My guru level is still firmly "beginner" but I picked up enough, and I used the software enough to get a good working knowledge of the MAC systems.] For a specialty combination of hardware and software specifically written to interact with each other, they crash a hell of a lot more than my Win98 SE ever did, or my XP pro ever has, through multiple iterations of computers, upgrades, and hardware.
Those that say MACs don't have issues and don't crash never use them. Period. End of discussion.
I've done everything from photoshop to 3d animation and rendering to multiple types of nonlinear editing as well as effects/rendering work for said rendering.
Good GOD what I wouldn't have paid for Adobe to write FCP for the PC all those years.
That and the fact that you really couldn't do much with their 1-piece hardware sets for ludicrous prices, you basically had to throw the machine out and get another instead of having any decent upgrade options for the longest time. That's not as much the case now, but for a long time they were like gigantic over-sized laptops with regards to the hardware inside.
So, like I said, as a guy that's suffered through MACs with some fairly decent heavy use over the past years, I can say I never ever ever want to have one as my PC. Ever. I just have too much stuff to get done without suffering the aggravation, and too little time to wait through freezes, hangs, and crashes.