I switched partly because I was impressed by the slick Mac OS X (did not like 9), but the motivation came from feeling like no consumer should have to after getting several error messages on a Windows machine. They would tick you off too, if you had any sense.
One of the worst was Windows Media Player: "INTERNAL PROGRAM ERROR." I clicked "OK," which was the only button. It was not OK. To me, that meant, "We don't know how to make programs work. Is that OK? You have only one option, to say OK." It wasn't OK, and after other problems, I switched.
Maybe you're miraculously lucky or blissfully insensitive to lack of professionalism, but the rest of the world is headbanging everyday because of Microsoft's mediocrity. This is partly due to Windows's popularity, but as a matter of fact, they're crashing all over, right now, and are also teeming with viruses. Frankly, Apple's ads make more sense to someone who has used computers enough to know and not so much that he's a blind fanboy.