messaging with “Net send” help

I have a network of 52 computers broken into four subgroups. Each subgroup uses one login name with an autologin. One group of 5 computers is “booking” etc. I would like to send a one way message to each subgroup of logins. I tried “net send” but itfinds the first occurence of the login and pops the message on that login screen ignoring the rest of the computers. I am thinking that I will have to create unque logins for the 52 machines but I would like to keep it simpler than this. And not useanother piece of software that wil require support.

We are running all machines on Windows 2000/ with a Win 2000 server.

Any ideas?