Im gonna back Steele, do it via the settings for your video card. It may not be the only way, just the only way thats worth a doing. Do it there and its a system-wide effect, do it in program and you have to do it for every program.
What vid card do you have Omega? I have an NVidia myself, and the display properties on it are quite easy to toggle in just that manner, I figure just about any card that has configuration software is just as easy, unless its an integrated card, in which case I cant help much.