Another thing too Mustang, You don't really have to be so cocky about everything you say. Instead, Just listen to what everyone has to say. You talk down to everyone like they are stupid and don't know anything about it. You're suppose to help, not put down. And btw I'm much older than you and actually work everyday fixing and tweaking computers. You could get a crappy FPS on Quake 3 even with a ATi 4870 if tweaked wrong. I don't try to make you sound stupid, I just try to give you information.
You also might be thinking but you had the TNT nvidia cards in 99 Designed for Quake 3 the the 2 3 and 4 families were all either MX or Ti Mx being the more afordable one.
Quake 3's gfx in a nutshell are based tightly around a "shader" system where the appearance of many surfaces can be defined in text files referred to as "shader scripts." Shaders are described and rendered as several layers, each layer contains a texture, a "blend mode" which determines how to superimpose it over the previous layer and texture orientation modes such as environment mapping, scrolling, and rotation. These features can readily be seen within the game with many bright and active surfaces in each map and even on character models. The shader system goes beyond just visual appearance, also defining the contents of volumes (e.g. a water volume is defined by applying a water shader to its surfaces), light emission and which sound to play when a volume is trodden upon.
So if your Open GL is not tweaked right on your card, The card will basically render these shaders incorrectly, Thus low frame rate or inconsist one. This basically happens when you go in and tweak your AA and AF. It's best to use the presets if you have no idea what your doing or you'll see a big dip in frames on all games. Or sometimes it can just be drivers are dated and It's time to update. =]