Excuse the double post.
For those wishing to upgrade to the latest firefox using the distro *buntu
Download the latest
Ubuntuzilla.deb and install.
Open terminal and:
ubuntuzilla.py -a install -p firefox
For the latest Thunderbird:
ubuntuzilla.py -a install -p thunderbird
For the latest Seamonkey
ubuntuzilla.py -a install -p seamonkey
Follow the prompts in terminal.
You will be notified of new releases in the future, just like when using windows.