The DirectX runtime cannot be uninstalled. We recommend Windows Me and Windows XP users turn on a "System Restore" point before installing. For information on turning on a restore point, please refer to the Microsoft Knowledge Base articles.
From Microsoft:
Microsoft DirectX is a group of technologies designed to make Windows-based computers an ideal platform for running and displaying applications rich in multimedia elements such as full-color graphics, video, 3D animation, and rich audio. DirectX includes security and performance updates, along with many new features across all technologies, which can be accessed by applications using the DirectX APIs.
