How do you unstick VGA mode in Win ME?

My system was running fine until I changed the Processor. Windows ME was and is loaded new drivers for my ATI Rage 128 Pro AGP Video card are loaded but the system will not go to greater than 640×480 16 colors. I have tried a different video card with the same results. I have completely reloaded ME with the same results. I looks like I need to do some serious Registry Editing but where?