Disable Proxy server change in IE in domain controller windows 2008 server

Wonder how to block certain domain users from internet surfing over the browser but retain the internet connectivity over the LAN?   You may consider by enabling the proxy server setting in Windows 2008 server's GPO at server manager screen.
1. Go to GPO and locate specific OU (organization unit) (If available) Select the OU and right click for "Create a GPO in this domain" ...It would open up the GPO editor..Just add a new entry to enforce the change.

User configuration\Policies\Windows Settings\Internet Explorer Maintenance\Connection\Proxy Setting
From there, add a fake proxy server address into it.

2. After that, go computer configuration\policies\administrative template\windows component\internet explorer\disable changing proxy setting  =  enable

With above setting, those user in that OU would be locked from changing the proxy setting.
Hope it would help..