HELP! DX9 problems!

Hey guys I've got a DX9 problem. I had trouble with Farcry it gave me some odd error in X64 after doing ALL the patches. So i went to reinstall (still don't know if this will fix it!) and the asked me if wanted DX9b, I didn't know if I had it or not. So I decdied to go to windows.com and now ther is a DX9C, but I can't install DX 9 C on X64!!!!!!!! How do I tell what version of DX I have? And how can i get 9c on my machine!

Okay so now its just major Far cry problems

to check what version you have. go to start run cmd. type in dxdiag. it should say near the bottom.