tengo windows vista. y como selecciono el usuario?
No puedes.
This command is only available in Windows NT, 2000, XP, 2003 and is unavailable in Windows 95, 98, ME, Vista, Windows 7 and later versions
Puedes cojer el comando MSG de Windows 7 (
ULTIMATE) e intentar utilizarlo en tú Windows Vista, O mejor aún, Actualizate a Windows 7 ya... chico xD.
MSG {username | sessionname | sessionid | @filename | *}
[/SERVER:servername] [/TIME:seconds] [/V] [/W] [message]
username Identifies the specified username.
sessionname The name of the session.
sessionid The ID of the session.
@filename Identifies a file containing a list of usernames,sessionnames, and sessionids to send the message to.
* Send message to all sessions on specified server.
/SERVER:servername server to contact (default is current).
/TIME:seconds Time delay to wait for receiver to acknowledge msg.
/V Display information about actions being performed.
/W Wait for response from user, useful with /V.
message Message to send. If none specified, prompts for it or reads from stdin.
Otras soluciones:
http://technet.microsoft.com/en-us/sysinternals/bb897553http://eng.dmessage.com/WinMessenger
Saludos.