Sims 2 DirectX problems.

I have finally gotten the video card to work and everything, but now whenever I try to play Sims I get the following message:

"Failed to find any directx9.0c compatible graphics adapter and have installed the latest drivers provided by the manufacture. This application will now terminate."

I know that this could mean that my video card is not compatible with DirectX, but this cannot be because my boyfriend has the same computer and when he put my video card in and installed Sims, everything worked perfectly. How come it is any different for me? If you have any idea on how I can fix this, please let me know.

I have spent hours looking all over the internet trying different instructions, nothing has helped. I have spent 75 dollars on this game so far and have had it since it first came out, yet have not been able to play it. This is getting extremely ridiculous.