Download the complete DirectX 9.0 SDK - (Summer 2004), which contains the FINAL release of the DirectX 9.0c Runtime and all DirectX software required to create DirectX 9.0 compliant applications in C/C++, and C#.
Major components include: DirectX 9.0c system components (runtimes); DirectX 9.0 Application Programming Interface (API) Documentation for each of the DirectX core areas (written for C++, and C#); DirectX 9.0c headers & libraries; Sample applications and source code; miscellaneous tools and utilities.
For additional information please see DirectX Web site along with reviewing the DirectX 9.0 Readme for last-minute updates.