1. This is NOT a Vista forum! This is a Windows 7 forum.
2. There is no DirectX11 in Vista! I believe Vista's DirectX is 10.1, but you cannot uninstall it because it is part of the Vista OS.
Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. ”