Running the below commands will fix your windows update issues on XP/2003 almost every time. This advice is repeated all over the web, not sure where the original source is.
Click Start, click Run, type cmd, and then click OK.
Copy and paste each of the following commands. Press ENTER after each command.
regsvr32 wuapi.dll
regsvr32 wuaueng.dll
regsvr32 wuaueng1.dll
regsvr32 wucltui.dll
regsvr32 wups.dll
regsvr32 wups2.dll
regsvr32 wuweb.dll |
After reregistering the dll's try microsoft update again!