When I go to System Properties in Control Panel, then to Automatic Updates the window is all grey and inaccessible to my cursor.
To make the Automatic Updates options configurable by the user (only for stand-alone systems), remove the restrictions. Since you didn't say whether you have XP Home or Pro, here are instructions for both versions.
Click Start, Run and type REGEDIT.EXE. Navigate to this location:
HKEY_LOCAL_MACHINE \ SOFTWARE \ Policies \ Microsoft \ Windows \ WindowsUpdate \ AU
In the right-pane, delete the two values AUOptions and NoAutoUpdate
Navigate to this location:
HKEY_CURRENT_USER \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ Policies \ WindowsUpdate
In the right-pane, delete the value DisableWindowsUpdateAccess
Using the Group Policy Editor - for Windows XP Professional Only
Navigate to the following location:
=> Computer Configuration ==> Administrative Templates ===> Windows Components ====> Windows Update
In the right-pane, double-click Configure Automatic Updates and set it to Not configured.
Then, navigate to this location:
=> User Configuration ==> Administrative Templates ===> Windows Components ====> Windows Update
In the right-pane, set Remove access to all Windows Update features to Not Configured.