Although the point should be made that lately, OS X is just as hard (or easy, depending on your viewpoint) to hack as Windows. They're both very good at keeping virus's out. The big issue now is that people (in general) are stupid and install programs that are adware or spyware. No OS will protect you from your own stupidity, and that is where anti-virus programs like Norton are good to have. As OS X becomes more popular, mac users are going to find out the hard way that they should be careful on OS X too.