DirectX 8.1 is sufficient for most gaming needs, but upgrading to DirectX 9.0 may be beneficial for future compatibility, especially as more games begin to require it. While some users report no noticeable improvements with DirectX 9.0, it is generally recommended to download it for broader support. OpenGL functionality depends on the video card drivers, and the opengl.dll file present in the Windows/system32 folder may not include all necessary components, as it could be a software implementation. Most applications requiring specific DirectX versions typically include the necessary files on their installation media, reducing the need for separate downloads.