Mozilla has finallydecided to deliver a 64-bit version of Firefox to users with 64-bit operating systems. Formerly these users were restricted to Firefox 64-bit builds for Linux distributions, or untested and unoffical Windows builds at the Mozilla x86-64 web site.
Disclaimer; this build is still a very early experimental build, handle with care, and very few plug-ins are available in 64-bit editions, only Java, and Flash non-final might work on this build. If you still want to help by testing it, then grab Firefox 4 64-bit nightlies at Mozilla public FTP server. File in bugs at bug#558448 (officially support Windows 64-bit builds). via [John O’Duinn’s Soapbox]