1) The machine is set up to run in LUA and
2) You have changed the Windows Automatic Updates from automatic mode to "Notify me but don't automatically download and install them" option.
In XP Prof SP3, this option is removed from the GPEdit template and hence one cannot set that with the policy editor. What a pity!
To allow non-Administrators to receive update notification in that environment, you need to do registry editing to defined the following registry key and named value:
This should allow non-administrators account to receive update notification. They can select which to install but often that requires a reboot.