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.