evil ubuntu package sources must check

To install the extra repositories, open a terminal window and type the following:

sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup
sudo gedit /etc/apt/sources.list

While in the editor, replace everything with:

## Add comments (##) in front of any line to remove it from being checked.
## Use the following sources.list at your own risk.
deb http://archive.ubuntu.com/ubuntu dapper main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu dapper main restricted universe multiverse
## MAJOR BUG FIX UPDATES produced after the final release
deb http://archive.ubuntu.com/ubuntu dapper-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu dapper-updates main restricted
universe multiverse
## UBUNTU SECURITY UPDATES
deb http://security.ubuntu.com/ubuntu dapper-security main restricted universe multiverse
deb-src http://security.ubuntu.com/ubuntu dapper-security main restricted universe multiverse
## BACKPORTS REPOSITORY (Unsupported. May contain illegal packages. Use at own risk.)
deb http://archive.ubuntu.com/ubuntu dapper-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu dapper-backports main restricted universe multiverse
## PLF REPOSITORY (Unsupported. May contain illegal packages. Use at own risk.)
deb http://packages.freecontrib.org/ubuntu/plf dapper free non-free
deb-src http://packages.freecontrib.org/ubuntu/plf dapper free non-free

Save the file and exit the text editor. Next type the command:

sudo apt-get update

you  will find alot of new packages like

sudo apt-get install build-essential
sudo apt-get install aircrack
sudo apt-get install kismet
sudo apt-get install airsnort
sudo apt-get install linux-source
sudo apt-get install linux-headers
sudo apt-get install sharutils