The video driver plus the MONITOR.INF from the monitor's maker.
You don't have to supply make and model numbers in your posts but when you omit details, replies can't be specific with maybe a link to the monitor's driver (MONITOR.INF) or more than how it works.
I am using a widescreen LCD monitor with a native resolution of 1280x800 pixels on a system running Windows 2000, and the display settings window refuses to give me the option to set the screen resolution to this value. (Or any other resolution with the proper height to width ratio.) After contemplating this situation for a while it occurred to me that I have no idea what defines the display resolution options that are available in that settings window. So my question is: How do I make the option for a 1280x800 pixel resolution appear on that display area selection slider? Or, more to the point, how do I convince Windows to stop being so unreasonably stubborn and just display an area of the desktop that is 1280 pixels wide and 800 high?