I’ve just updated my stable version of Firefox 3.0.3 to the latest Firefox 3.1 beta 1. I know I am putting my web browsing experience at risk because Firefox 3.1 is still under testing and development. So far so good as I still haven’t experience a single crash yet. It is able to load and end the firefox.exe process much faster than the current version when I close it. Firefox 3.1 introduces a new tab switching preview which I didn’t like so I disabled it.
One biggest …

All firefox passwords are stored in three files
signons.txt, signons2.txt, key3.db
These files are stored in your firefox profile folder.
In Windows XP firefox profile is at:
c:\Documents and Settings\WindowsUsername\Application Data\Mozilla\Firefox\Profiles\profilename
Copy these three files and save them where ever you want and if you want these passwords in your other os also then just replace these three files.