Thanks for the replies...
I think you have missunderstood what it is that I'm trying to do...
for example...
You dial into a ras connection using your modem. I want the NIC disabled on the machine the second the Modem starts talking.
on the flip side...
You are connect to a network with your NIC. I want the modem diabled until you disconnect from the Network.
does that help with the idea... it's not as simple as disabling the device, this needs to happen automatically, and not be a manual process...