JSI Tip 0122 - Network Neighborhood System Policy Restrictions.

If you don't want to remove Network Neighborhood from the desktop (see tip 050, "Locking down that desktop"), you can add the following network restrictions:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Network

Add Value of NoEntireNetwork as type REG_DWORD. Set it to 1.

        and/or

Add Value of NoWorkgroupContents as type REG_DWORD. Set it to 1.