Ye' old general discussion board. Basically, for everything that isn't covered elsewhere. Come here to shoot the breeze, shoot your mouth off, or whatever suits your fancy. This forum is not for asking programming related questions.
Usually, it's set up by the usual way of adding monitors, or by the drivers. In the case of ATI, it's usually the drivers that set it up, but I've had ATI's that do it through Windows' dialog and the driver too.