I need a utility that can popsup messages on
an windows platform, the requirement is, i have a lan
network running on a linux server, i need to send
messages like rebooting or something like that for
users to know that there is some problem due to which
the network willbe closed for some time.

please let me know about it.

or even a client based software would do on which i
could send messages and the message would popup at the
client's windows machine.