I work on a network with over 5000 workstations and sometimes need to
broadcast a message to all users logged on.

I currently have a program that was home-made by someone who is now
long gone. All this program does is create a "net send" to every v-lan
on the network. We know how to use it and know how to manually add the
v-lans in the db; however, my boss wanted something "professional" and
maybe even from a company that provides support.

Is there software out there that does that? Software that sends a
small pop-up to every computer on the network.