The Lenny "businesscard" iso at
http://cdimage.debian.org/cdimage/release/current/i386/iso-cd/debian-503-i386-businesscard.iso
is only 36 MBytes.
It contains everything you need to start the installation. It will
dynamically download all the other packages you need for your
*particular* installation, and *only* those things. When you are
bandwidth constrained, it's by far the best installation method for
minimizing total waiting time.
And, it has the advantage of automatically giving you -- as an integral
part of the installation process -- all the security and stability
updates that have happened since the distribution was created.