The thing I love about using the Mac is that even as a IT professional, and a guy who made a lot of money over the years cleaning up spyware and crap..it's nice to just be able to browse without stupid shit happening to your machine without a half dozen prevention apps, firewalls, registry lockers, being careful not to click on the wrong part of a popup box, ect.
Browsing on the Mac is just a much more enjoyable and low stress experience than the flury of popups, warnings, intrusions, ect that can affect IE. I never really cared for Firefox so I always stuck with IE.