bolongo, is your plan to use PHP with a webserver on your Ubuntu machine? If so, I would recommend checking out some of the amazing how-to documents on howtoforge.com. Some good examples:
'the perfect desktop':
http://www.howtoforge.com/the-perfect-desktop-ubuntu-11.04-natty-narwhal-with-ubuntu-classic
'the perfect server'
http://www.howtoforge.com/perfect-server-ubuntu-11.04-ispconfig-3
You can probably skip a lot of the steps if they don't apply to you (like skip installing BIND or spamassassin if you are just running a dev server).
If you want to set up a LAMP system, I would recommend starting where it says to install MySQL, then Apache and PHP5.
