Creative ideas for monitoring network

This is slightly off topic, but I'm wondering if anyone can help me with something. I work on a network that is NT 4.0 SP4. We have a LAN with around 150 users tied to several other LANs. I need a way to notify certain users when the network goes down. I need this system to be as automated as possible.

I could install a programs such as What's Up to do the job, but this project is not a mission critical one. I considered making a batch file with a bunch of net send commands, but that in iteself would not work. I don't really want to buy software to do this. Anyone run into this?

I believe you can use the net send command and send a message to a domain--it works with W2K, but I can't recall if NT4 has it or not.

what we use where i work is pc anywhere 9.2 I manage about 900 computers and pc anywhere lets me do a mass update and even chat with the user. yes it can be a secruity issue if you let the information about login out but its realy very useful. what you do is basicly take total control of any computer on your network and see exactly what thay see. it is made by the same people that make norton antiviris. realy cool stuff. if you find any thing deffernt please post it.