update firefox 3.6 with 4.01

This is the best way to install Firefox 4 on an Ubuntu system prior to Ubuntu 11.04:
http://www.ubuntugeek.com/how-to-install-firefox-4-in-ubuntu-using-ppa.html

sudo add-apt-repository ppa:mozillateam/firefox-stable && sudo apt-get update && sudo apt-get install firefox

guess I did what U suggested (sudo add-apt-repository....) yet my version is still Firefox 3.6.

is there anything else I have to do?

Can you give the output of:

lsb_release -a; apt-cache policy firefox

Thanks

After pasting the line from #4 into the terminal, the following output came:

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04.2 LTS
Release: 10.04
Codename: lucid
firefox:
  Installiert: 4.0.1+build1+nobinonly-0ubuntu0.11.04.1~mfs~lucid1
  Kandidat: 4.0.1+build1+nobinonly-0ubuntu0.11.04.1~mfs~lucid1
  Versions-Tabelle:
 *** 4.0.1+build1+nobinonly-0ubuntu0.11.04.1~mfs~lucid1 0
        500 http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status
     3.6.17+build3+nobinonly-0ubuntu0.10.04.1 0
        500 http://archive.ubuntu.uasw.edu/ lucid-updates/main Packages
        500 http://archive.ubuntu.uasw.edu/ lucid-security/main Packages
     3.6.3+nobinonly-0ubuntu4 0
        500 http://archive.ubuntu.uasw.edu/ lucid/main Packages

Thanks so much, my friend.