DirectX is software that allows your game to communicate with the hardware on your computer.

IMPORTANT: Before updating DirectX, check with your hardware manufacturer to ensure that your video and sound cards are compatible with the latest version of DirectX.

There is no way to uninstall or roll back this upgrade. If you are running Windows XP Service Pack 2, Windows Vista, or Windows 7, then you most likely already have the latest version of Direct X. If you are not sure, the easiest way to get DirectX is to perform a Windows Update.