My experience is, you use a Mac if you ether do very basic graphic design or you dont do much around a computer to begin with and you want to be hip.
You use a PC if you want to get work done.
Ive had nightmares using Macs. I remember one time I was doing a video project and I tried to save it. I just started it, so I picked a folder, then a name, then hit save, only to get a very interesting message:
Cannot save the file because file does not exist.
Only on a mac...