I don't think that MSG.EXE will broadcast - you would need to send to each machine.

You could code something really smart using multicasting with repeaters at each of your sites, but that's a *lot* of work and means getting into socket level network coding.

If you can't find anything ready-rolled I'd suggest a web based solution. You could maybe leverage RSS feed technology, or simply check the modified-since attributes of a page and pop it up in a browser if it has changed. That way staff would get older news items that had occured while they were logged off.

If your check interval is say every 10 minutes the load shouldn't be too bad.