The radeon 4850 would have a real problem keeping up with a 2500x1600 resolution. If you want the best image quality you can get with a 4850, you're going to want to stick with 1680x1050, maybe 1920x1080 since you have the 1gb version. I also have never in my life seen a small monitor with 25x16 resolution- thats crazy high pixel density. The image quality that would be effected by higher resolution is going to end up being similar if you have a smaller monitor with lesser resolution compared to a larger monitor with higher resolution. I would suggest if you are getting a 19-20" display, get a 1680x1050.