You need to put windo size x to 1280 window size y to 1024 and turn full screen bak on then install the driver. After you install if do not touch the config cause it will uninstall the driver just start up the game it should work fine.
Okay, you don't seem to be clear on the concept here.
The OpenGL Driver users a config file (ff7_opengl.cfg, if I remember right). You can touch this all you want before and after the driver is installed, and it will safely change the driver's settings. You might break things, but you won't uninstall the driver.
The original game uses FF7Config.exe for configuration settings. Running this will uninstall the driver, and you'll have to run the registry changes again.
So touching "the config" won't kill the driver. At all.