As Microsoft continues work on Internet Explorer 9, the other big browser players are starting work on beta versions as well.
Mozilla has recently released their 4.0b1 for Windows and makes the 7.7MB download available for all to try out.
Of course as with any beta software there are caveats and warnings so make sure you heed them or backup your system before you install it or any beta software. Windows 7’s System Restore is your friend.
Some of the know issues with the Windows version provided by Mozilla are:
Some graphics drivers may not work properly with full screen Ogg Theora HTML video acceleration (see bug 564391) When using a Persona, the maximize, minimize and close window buttons will not appear, though they will still work (see bug 574833) When using the Windows "Classic" theme the toolbars and tab strip may appear gray for several seconds as Firefox starts up (see bug 574638)