Mozilla 3.0 for windows and Ubuntu

Use below link to download Mozilla 3.0

http://www.mozilla.com/en-US/ --- windows

Ubuntu --follow the steps mentioned in the below url,it will do all the backups then it will install
Here one change we need to do during the installation
sudo tar -C /opt -jxvf firefox-3.0b2.tar.bz2
instead of this make modification like this
sudo tar -C /opt -jxvf folder/firefox-3.0b2.tar.bz2

Refer:
http://www.ubuntugeek.com/howto-install-firefox-3-beta-2-in-ubuntu-710-gutsy-gibbon.html