Grow a brain. Did you not have one in the first place? Or did your Mac eat it?
Whenever I meet someone advocating Mac, I ask them the same question: "Why?" and I always get the same answer: "Because Apple is better." Even when I push for reasons and details all I get is the same unsupported statements over and over. If someone out there can give me a firm, logical, and above all supported argument that Macs are better than PCs then I will listen. As it is I have seen just as many computer problems with Mac software as I have with Windows, I know that it is less compatible than Windows for most things, creative software (contrary to popular opinion) does not run better on Macs, and by buying a Mac you are not going against the corporation because Apple is at least as big as Windows.
What annoys me the most, though, is that Mac users won't give me a reason to believe Apple is better. It's as though they expect me to believe them for no reason and that is belittling my intelligence. So far I have heard similar arguments (or lack of argument) only from politicians, racists, supreme idiots, and my siblings (but not since they were 12). Please don't make me group you with these people, Mac users.
Edit: Okay, someone did give me one reason, which I admit is a fairly good reason, but not enough for me to switch computers and not enough to endear me to Mac users. Thank you anyway, though.