If you haven't already configure an ADDS with the server as the domain controller (will require dcpromo.exe).
1. On the domain controller open group policy management
2. Expand down to your default domain policy (or another one if you want to use it, best practice would dictate not editing the default domain policy)
3. Right click the default domain policy, click edit
4. Under user configuration, expand to User Configuration\ Administrative Templates\Control panel and edit the items there
5. Now add your Windows 7 machine to the domain, by doing this the default domain policy will take effect and any standard user will not have the ability to go into the control panel.