Please Help - Tricky Question

[Gary007]

I am building a replacement for WinPopup and I would like to be able to send messages to people using their username and their computer name. I also need this for backward compatibility with the original Microsoft edition of WinPopup.
When a user sends a message for the original WinPopup it is sent from the "Username" of that person so my program cannot determine the computer that sent the message. My program must send the message to the computer name and not the username.

I am using a combination of windows 98 and 95 so the Windows NT way of doing this is no good. If someone has a way of working this out could they please reply urgently.

Thanks

[CyberSurfer]

Dart.com have a UDP control that broadcasts messages to every machine on your LAN using the UDP port.

[Gary007]

The program I made is working perfectly but there is the one small hitch. When someone sends a message it could be from their username and therefore my program will look that up in the list of computer, but it wont be there.
I need a way to make it automatically work out the usernames.

[Gary007]

My program can already send messages from the current computer but it is Microsoft's version of winpopup that does not send from the computer name it sends from the username. This is why I need to determine the username on a particular computer.