Send messages to other users on network

[Z]

Ok, I know this is gonna sound stupid but I have three computers in the house that are all connected via a wireless router which is connected to a cable modem. The question I have is that is there someway i can message a person on another computer that is on the network, kind of like an instant messenger but built into windows. By the way I'm running windows xp on all my comps. Its a pain in the ass going up and down two floors. I'm guessing there must be some way of doing this in the command prompt or something. Any ideas or suggestions will be appreciated. Thanks

[Guest]

Use Windows Messenger. Start>Control Panel>Administrative Tools>Services>Messenger

[Z]

I did a little more research on the web and found that one can use the net send command in dos. I tried it out but am having slight trouble.
When i type
net send * Hi
the message is sent to all the computers however when I try to send the message to one particular computer i get an error message:
net send officecomputer Hi
An error occured while sending the message to OFFICECOMPUTER
The message alias could not be found on the network

Does anyone know what I might be doing wrong ?

Thanks

[Major_A]

standard format should be net send <computername/ip address> <message>

Make sure these are windows nt/2000/xp machines and that messaging service is enabled/turned on.