Relating to that
Virus Scanning entry I think
Debian Volatile is better for an up-to-date ClamAV than
Backports.org.
Debian Volatile is made for packages that change very often, and you need the current upstream package on a server. Like an up-to-date virus scanning engine.
So simple and this line to your
sources.list and run after that an
apt-get update.
deb http://ftp2.de.debian.org/debian-volatile sarge/volatile main
BTW:
Volatile Mirror List
Now you can install your clamav normally with an
apt-get install clamav.