I have users that create a vpn connection off of my 2008 Terminal servers and try to connect to other customers. I want to prevent them from making vpn connections.

I presume you mean they are running the vpn client while in terminal server and creating an outbound connection to a remote machine. If you mean RDP, then I would need to chang my answer slightly. If you have the ability so, I would actually modify the firewall not to allow outbound VPN connections from that particular server (if you make it global, obviously it would affect company wide rather thant just that one server). Good Luck, James