Optional Start of OpenVPN at boot time

[ArnoldGoat]

At our school we have a Win2008 R2 server network with W7 and XP clients. When teachers work from home, they use RDC to a Terminal Server, and get a session similar to their normal laptop login experience. I saw that OpenVPN could do ethernet bridging, so I hope that I can simplify things for the teachers so that wherever they are, the behaviour is pretty much the same and they don't have to bother with the RDC thing.

I have configured an OpenVPN server on a HyperV W2k8R2 server hosted on a DC as an ethernet bridge. I have configured a W7 x64 laptop as an OpenVPN client, which connects as a system service at boot time. I am amazed at how easy all this has been! The machine connected to the school server on boot, and did its Group Policy stuff at boot time, and at login time. (Just a few problems with the home drive which I can probably sort.)

The thing is this. When I take the laptop into school and connect it to the real network, is there some easy way to stop all the VPN stuff happening. The only thing I can think of is to leave the service as manual start, and have a program which looks at the IP address. If it's in the school range, do nothing, otherwise start the service. But is there a better way?

Ken