Not really. Oblivion and Fallout 3 both scale up very well with better hardware..............not only did it run much better but it looked much better as well. I also played Fallout 3 @ 1280x1024 and then I played it @ 1920x1080 and it looked like a totally different game.
Higher Resolutions will look better than lower ones. That I agree with. And, some graphics cards look better than others. For example, ATI tends to look more rich in colors, but not as sharp and crisp as Nvidia. It is subtle and a matter of preference to what you like.
However, I doubt that any graphics card running at a particular resolution would look dramatically different than another graphics card at the same resolution on the same game at the same settings. Subtly different? Sure. Would you prefer one over the other? Maybe.