Lock down Connection Tab in Internet Explorer

Go to "Run" and type gpedit.msc
Click on "User Configuration"
Then "Administrative Templates"
Then "Windows Components"
Then "Internet Explorer"
Enable the policy that reads "Disable Changing connection settings"

The LAN connection tab will be grayed out. This will effect all users who log in. The registry entries can still be changed to relect new proxy server settings. This is currently done via a Kixx login script