Although Mozilla doesn't officially release a 64bit build of Firefox and Thunderbird, they do build them along with the 32bit version. The builds you get from Ubuntu repositories are 64bit.
If you want to get the latest Firefox 5 and Thunderbird 5 on your machine, completely uninstall Ubuntuzilla and install the mozillateam ppa:
Code:
sudo add-apt-repository ppa:mozillateam/firefox-stable
sudo apt-get update
sudo apt-get upgrade
Code:
sudo add-apt-repository ppa:mozillateam/thunderbird-stable
sudo apt-get update
sudo apt-get upgrade
Those repositories are maintained by the people responsible for Firefox and Thunderbird on Ubuntu.
For additional info, see Firefox 4,5 & Beyond Mega Thread
Bookmarks