Civilization 4 Installation Help?

Ive had Civ 4 and the Warlords expansion installed for 5 months now, and recently I made an account on gamespy so I can be able to play online. It told me that I had to install a patch, so I did and then went to restart my game but when I click on the desktop shortcut to open it, is says; The application has failed to start because D3DX9_ 32 was not found. Re installing the application may fix this problem. But i dont want to if i dont have to because I dont want to lose any of the saved games I have. If worst comes to worst and I have to reinstall, do I have to reinstall both games or just the main one???