After running a repair install of XP, Windows Updates may not work correctly.  It'll tell you that you have updates, it'll download them without problems, and it'll even try to install.  This is where the error will be seen:   "The following Updates were not installed".
This will continue to loop untill you resolve it.

To remedy the problem, certain "dll" files associated with the Windows Update agent need to be re-registered with the operating system.  It's not as daunting as it seems.  I put together a batch file to do it for you.  Download:  Update.bat
to your Desktop or any other place that you can access easily.  Double click it to run.  Once the little black command window has closed, it has finished and Windows Updates will work properly again.