Knoppix 4 kids? I can't even keep up with all of the variants anymore.

As root, edit /etc/apt/sources.list. The following should work.

deb ftp://archive.progeny.com/debian/ testing main non-free contrib
deb http://non-us.debian.org/debian-non-US testing/non-US main contrib non-free
deb http://security.debian.org/ stable/updates main contrib non-free

If you don't want testing then just change all instances of testing to stable. Don't forget to do apt-get update (as root) after adding these sources.