Prevent Network Administrators from access to sql database tables

I have an employee database and I want to restrict access to specific tables to only a couple of people not including the Network Admins. What would be the best way to go about doing this seeing as though they know the sa username and password? I thought about creating a group in Active Directory, then a role within SQL Server that denies that specific group access; however, they could just remove their name within the group and again have access.
I realize this is probably an obvious question but any suggestions would be helpful. Thanks

Using SQL Server 2000