Re: Somewhat simple way.
Lock down the GHP long enough for windows to try to dial home, then later check the log to see where (IP and port) it was trying to connect to. You may be able to block access just to that port or IP and still be able to use GHP for normal connections.
~~~)-Steven----
"I want you to remember that no bastard ever won a war by dying for his country.
He won it by making the other poor dumb bastard die for his country..."
General George S. Patton