Internet explorer has been the dominant browser since as long as I can remember. Despite the warnings of its security flaws, it always seemed to work. However I believe its finally met its match.
Firefox has plenty of improvements and ease of use that make it a fast growing rival to the king. The feature that most stands out to this user is tabbed browsing. It is much more convenient to jump from tab to tab than to have lots of open windows. Especially if you like to have a lot of windows open at once. What I love is the security.
In IE, for me at least, certain web sites will not remove from history. I like my history to be clean at the start of each day. Right now my IE has web sites that are there even if I delete history, off-line files, and cookies. Firefox removes history and other data cleanly. I get a fresh start everyday. Firefox also has a feature to disable flash. Which can come in handy on highly "flashy" sites that distract you away from the content.
Firefox is providing to be a better browser. It will be interesting to see what IE conters with in IE 7.