In order to use the officials debian sources
paste this into your sources.list
#nano /etc/apt/sources.list
## 2 - Official Lenny
#deb http://http.us.debian.org/debian/ testing main contrib non-free
#deb-src http://http.us.debian.org/debian/ testing main contrib non-free
#deb http://http.us.debian.org/debian/ testing-proposed-updates main contrib non-free
#deb-src http://http.us.debian.org/debian/ testing-proposed-updates main contrib non-free
deb http://http.us.debian.org/debian/ lenny main contrib non-free
#deb-src http://http.us.debian.org/debian/ lenny main contrib non-free
deb http://http.us.debian.org/debian/ lenny-proposed-updates main contrib non-free
#deb-src http://http.us.debian.org/debian/ lenny-proposed-updates main contrib non-free
Full list here
http://www.sourceslist.eu/sourcesdebianlenny.list
