Also, so you aren't completely lost after the install, here is a few useful tid-bits of information.
1. sudo. sudo will get you temporary root access. Use sudo in front of another command, such as "sudo apt-get install <package_name>"
2. apt-get install. This will be your main means of installing packages in Ubuntu. Ubuntu is a Debian derivative and that means it uses the same installation means.
3. sudo su. Complete and total rootness. 1337.
4. cd /file/path. If you ever need to go into a directory, this is how. cd, then the path to the directory. "cd /home/blah/games/file"
Those are my most frequently used commands. Do a Google for a complete list of commands and their uses.