They will have probabaly said that you could play the game because your card does meet the minimum requirements, but never expect a card which meets the minimum requirements to run well.
Let me give you another example. I have a X850XT which is a rather good card, however even with this good card I can't enable full shadows in games like F.E.A.R, AoE3, Serious Sam 2 etc. This is because my card does not have Pixel Shader 3 or HDR support so that would mean that I would not be able to even activate those graphic settings in the games. They will be greyed out and unselectable.
This is the same problem you have. A minimum requirements card can't run the game the way it's supposed to be run.