Wow I just saw on the Firefox download page that they have passed 500 million downloads today. That is a helluva lot of installs. The number is a bit warped becuase some people like me have downloaded it 10 times or so to different computers but still according to my stats around my different websites Firefox is being used by about 20% of average visitors (this is on non techy sites).
I have mentioned before how much and why I love Firefox but the extensions are great, the adaptability is great and the security to me is not really an issue but everyone raves about it anyway.
I do use Internet Explorer still to access out Sharepoint portal but other then that Internet Explorer on my machines tends to be only for the Microsoft Updates to XP