Don’t forget that the rest of the computer needs to be considered. You can put an awesome graphics card in a not so awesome system and get a totally different experience. One critical issue would be if the speed of the graphics card slot (4x, 8x, 16x, etc.) is less than the max speed of the card itself. The card will still be usable but with much less performance.
So, it would help to know the rest of the system’s specs (e.g. CPU, speed/type of video card slot, RAM, cache, screen resolution used when running the game, etc.) before determining how well the game really runs.