Nice, I'm gonna try this with my brother lolgo to start>run> type in "services.msc" (without the quotes). then make sure the messenger service is enabled. then go to start>run>type "cmd" (without the quotes). then type:
net send NAMEOFPC MESSAGE
for example: net send dudese this is my message
btw messenger must be enabled on both pc's.
But when in my account where I work when I try to change the screen settings it prevents the operation...And the message in from Windows...that is built into windows. dont think theres an official microsoft program though. only third party network messengers.