Use the DirectX Control Panel, which is installed automatically with the SDK, to examine and modify the properties of DirectX components. The tool is launchable from the Start menu under Programs, Microsoft DirectX SDK, DirectX Utilities. This tool contains tabs for each DirectX component. Using this tool you can:
The control panel has a Managed tab, which contains the names of the DirectX Assemblies that are installed. For any assembly that is installed in the Global Assembly Cache (GAC), you can find the version listed under each assembly name by right clicking on a particular assembly version and selecting Properties from the popup menu.