I am a big Firefox supporter and use it over Internet Explorer whenever I can. Mozilla has posted the latest Firefox browser version 1.5 Beta 1 (Deer Park). It can be downloaded by visiting the Mozilla Firefox Project here.
The release comes on the eve of Tom Ferris of Security Protocols uncovering and exposing a security flaw (IDN buffer overflow security issue) that affects all versions of Firefox. Mozilla has addressed the problem with a patch that can be found here.
