Hola, para usar Sarge (mientras este como testing) puedes usar esto nada mas:
> # /etc/apt/sources.list for Knoppix > # If you want to do a "full upgrade", you should first > # upgrade the Packages from Debian/unstable (KDE & Co.) > # before doing a (dist-)upgrade for Debian/testing. > # > # See sources.list(5) for more information, especialy > # Remember that you can only use http, ftp or file URIs > # CDROMs are managed through the apt-cdrom tool. > > # Testing deb http://ftp.rediris.es/debian testing main contrib non-free deb http://ftp.rediris.es/debian-non-US testing/non-US main contrib non-free # Testing Sources deb-src http://ftp.rediris.es/debian testing main contrib non-free deb-src http://ftp.rediris.es/debian-non-US testing/non-US main contrib non-free luego haces un apt-get update y despues un apt-get dist-upgrade. Saludos