5. Originality
In the most recent version of IE 7, you'll find a lot of cool new features - unfortunately, almost all of these features have been in Firefox for years now. With Firefox, you'll have the latest and best features straight out of the box.
4. Cleaner Interface
Firefox's interface is clean, and easy to use. Additionally, you have the ability to customize the navigation to just about any specification, as well as easily implementing thousands of new themes to personalize Firefox.
3. Easy to Use
If you know how to use Internet Explorer, you'll know how to use Firefox - all of the keyboard shortcuts are the same, and Firefox will import your bookmarks and settings for you, meaning no learning curve for you. Just download and surf.
2. Free and Open
Firefox is completely free and supported by a dedicated community of developers to constantly make it better. since it's "open source", that means that anyone can make improvements to the software and could possibly make it into the next release of Firefox.
1. Customization with Plugins and Extensions
The real power of Firefox lies in it's added functionality through the use of 'extensions'. Thousands of developers program small additional tools for the browser that allow you to do almost whatever your heart desires, and make your life easier.

http://www.mozilla.com/firefox/

Yeah, Firefox pwns everything.

Firefox has been my favourite browser since I heard of it from this funny mean boy named Benny! That was just a memory of mine from about 6 years ago.