Windows Update does not start in Windows XP, Windows Server 2003, or Windows 2000
If you try and update Windows after you update to service pack 3 in Windows XP and it doesn't work.
Try the below
If you don’t have the latest Windows service pack.
If you are running one of the following operating systems, make sure that you have the latest service pack installed. If you
don't have the latest service pack installed, click the following link for the appropriate operating system to install the service pack.
To turn on Automatic Updates manually, follow these steps:
To turn on Automatic Updates manually, follow these steps:
1.Exit all programs that are running.
2.Click Start, click Run, type sysdm.cpl, and then click OK.
3.On the Automatic Updates tab, click Automatic (Recommended), and then click OK.
4.Click Start, click Run, type cmd, and then click OK.
5.Type wuauclt /detectnow, and then press Enter.
After you turn on Automatic Updates, wait one hour, and then scan for updates again.
If the above does not work, update the Windows Update agent and install.