So you want to downgrade from VISTA to XP??? I never did that, as I like vista, so I don't really know how you would do that...
Disabling auto update, follow these directions...
If you are using the default control panel, follow these directions...
1. Click START.
2. Click CONTROL PANEL.
3. Click SECURITY.
4. Fine WINDOWS UPDATE.
5. Under WINDOWS UPDATE, click TURN AUTOMATIC UPDATING ON OR OFF.
6. Choose your option from the 4 available options.
7. Click OK .
8 Close the CONTROL PANEL window and you are done.
If you are using the classic control panel, follow these directions...
1. Click START.
2. Click CONTROL PANEL.
3. Double-Click WINDOWS UPDATE (should be at the bottom of the page).
4. On the left side panel, click CHANGE SETTINGS.
5. Choose from the 4 available options.
6. Click OK.
7. Close the CONTROL PANEL windows, and you are done.
I hope this helped you...