In Microsoft Public Windows XP General News Group,I was going through a starge request-"Accidentally XP SP2 has been downloaded and it is asking me repeatedly to be installed.How to stop this annoying pop up?"
How To Stop Or,Turn Off Automatic Updates:-
Start>Right Click On My Computer>Properties>Select Automatic Updates>Click the radio button against Turn off Automatic updates>Ok/Apply
Warning:-Doing this your computer may be more vulnerable unless you install updates regularly.
"How to configure and use Automatic Updates in Windows XP"