How to prevent Windows Update from downloading and installing Windows XP Service Pack 3 automatically.

1. Click Start > Run.

2. Type regedit and click OK.

3. Click the plus sign next to HKEY_LOCAL_MACHINE
then Software
then Policies
then Microsoft
then Windows
then click WindowsUpdate

4. Look for an entry on the right side for DoNotAllowSP. If it doesn’t exist, you will need to create it. To do so, right-click on WindowsUpdate and select New > DWORD Value. Give the value a name of DoNotAllowSP. Press the Enter key when you are done.

5. Right-click the DoNotAllowSP entry and click Modify.

6. Set the Value data to 1 and click OK.