To install updates that have been downloaded
In Windows XP Home Edition, you must be logged on as a computer administrator to install components or modify Automatic Updates settings. In Windows XP Professional, you must be logged on as an administrator or a member of the Administrators group. If your computer is connected to a network, network policy settings might also prevent you from completing this procedure.
Windows might prompt you to restart your computer after certain components are installed. Please restart your computer when prompted; otherwise, your computer might not work properly.
Windows notifies you when installation is complete.