As splattne correctly points out, you can hide the Display Settings tab using policy. In AD Group Policy, it's under
User Configuration > Policies > Administrative Templates > Control Panel > Display > Hide Settings Tab
However, all this does is exactly that: hide the settings tab. It will not stop advanced users from changing the resolution, especially if you have a tray application or shell extension installed by your graphics card driver that allows users to do this.
Unless someone has a better method, I would add the AD group policy above, and uninstall or disable or otherwise lock down any Intel/ATI/NVidia application that allows users to change the resolution. This isn't bulletproof, but it should stop all but your most technical users.
A truly bulletproof solution to preventing resolution changes under non-administrator accounts might interfere with certain fullscreen applications.