Registry Hives in Windows 2000

Folks,

I just want to disable the LAN “Proxy Settings” of Internet Explorer through Win2000 registry. We are connected to LAN and was able to surf ONLY the INTRANET without having a Proxy Server in the proxy settings field.
I want to limit totally all my users not to surf the INTERNET but these users are wise enough to know our Proxy Server thats why I want to disable the LAN Proxy Settings field. All my users are running on Win2000 machines.
Hope you can help me on my problem.

Thanks