If the box has a connection to the internet all you need to do is the
following:
1) Open as root the file /etc/apt/sources.list with your favorite editor
and uncomment or add if missing the folowing lines.
deb http://http.us.debian.org/debian sarge main contrib non-free
deb http://non-us.debian.org/debian-non-US sarge/non-US main contrib non-free
deb http://security.debian.org sarge/updates main contrib non-free
WATCH for the sarge word instead of woody or stable, this tells apt-get
which is the release you want.
Comment any other line in the file.
2) As root run apt-get update.
3) Again as root run apt-get dist-upgrade, sit back have a smoke or
whatever you fancy, and watch your old reliable Woody turn into a lean mean
Sarge ;-)
Somebody correct me if I'm wrong please.