NIS 2009 Add-On Pack and Microsoft Updates Problems

Hi!  I was unable to find a thread that gave information on the issue I am reporting.  The issue is that NIS 2009 Add-On Pack does not allow Microsoft Update to work on a Windows XP Professional SP3 system correctly.  The only work around I found is to remove the add-on pack altogether.  Please advise.  (My system is P4 Prescott based w/ 2GB memory.)