You could look at it like this, if you wanted. The less of your graphics card is used to run a higher resolution, the more is available to you for things like anti-alaising, or higher frame rates. The same is true in reverse: the more of your graphics card you use to push a higher resolution, the less you would be able to turn up settings in games. While there are some caveats to those statements, generally they are true. Get the 6850 and if you aren't happy with your screen size later, buy a better monitor.