Debian is free by default, AFAIK. However, Debian still has some issues:
* On boot Debian alerts users to non-free firmware that they don't have.
* Debian installation apparently sometimes leads users to non-free
repositories.
* I'm unsure if Iceweasel (Debian web browser) is packaged with non-free
recommendations removed or not.
PS. Changing your sources.list is probably not a good idea :o
http://www.linuxquestions.org/questions/debian-26/using-dist-upgrade-to-upgrade-from-debian-to-ubuntu-583736/
and http://linuxmafia.com/faq/Debian/downgrade.html
