Linux.com: "Firefox 4.0 is still a bit away from final release, but the time to think about switching is now. The Mozilla Project is releasing Firefox 4.0 beta 6 this week, and the current builds are really good.
Why switch? I'll give you five excellent reasons to jump on the 4.0 train today."

Originally an experimental branch of the Mozilla project, a new web browser was launched on November 9, 2004: Firefox 1.0.