Jeff in Seattle, having read and participated in several of these types of threads, I must warn you that the solution isn't going to be 100% technical. It's going to be a mix of technical solutions we can offer combined with your own set of rules and policing. Unfortunately, setting controls on the computer is only going to lighten your policing burden, but it certainly won't remove it.
Group Policy is going to be your friend here. Duzzy offers a couple good suggestions, but you're going to want to read up on what you can modify in group policy to give you the rules you desire on the computer.
Local Group Policy Editor - Open
Local Group Policies - Apply to All Users Except Administrators
Group Policy - Apply to a Specific User or Group