Nimey asks: "I support two computers which need Internet access to one website; they also are used to drive scientific instruments and so have proprietary scientific data. They run Windows XP SP2 because the instrument software requires IE, an ActiveX control, and .NET 1.1. Both machines are in a Windows 2003 active directory. Because of policy, it's not possible to redirect their network traffic to another box for filtering, but they are NATed. I want to restrict their network access to that one website (HTTP/HTTPS, possibly FTP) and to the file servers on the network (SMB). Can I enforce this in a way that's not changeable by a user?"