While I agree mobrocket with what you said about security, I don't really agree with what you said about mac users not knowing their systems to well.
Virus security has never been a "huge" issue with mac, because lets face it, there weren't any designed for them that people know about.
As for the average mac user, a lot of people just don't like messing with systems all the time, or like to go to an actual brick and mortar store that can provide you service on a product they specialize on... Not many computer stores can say that. How many computer companies control everything from software and hardware to their actual in-store experience?
That being said, I had an Apple that had Linux, Windows, and Mac OSX on it running at the same time, and was just awesome to make sure everything was compatible with websites.