Version 1.5 RC1 of the new Firefox Beta (formerly Deer Park) is now available from Mozila's site
at a small 5.0MB. The current stable release of Firefox is 1.0.7, but if you are into the latest and greatest and don't mind experimenting, you might want to give 1.5 a try. It has some very nifty toys with it such as a better popup blocker, update “patches” rather than full updates, the ability to drag and drop tabs (I definitely enjoy this) and more. This last release has been focused on bug fixes. Keep in mind that it is a beta, and no official support is available... but without user input, a beta never makes it to release. If you are into new stuff, try it out.