WUA running context used to install update

This might be useful for 3rd-party update developers.

Description Context Used to Install Update
Site

This is when you go to http://www.update.microsoft.com directly for updates.

This is only used for pre-Vista systems

The current user account
WU App

This is for Vista/Win7 system.

This is when you go to Control Panel -> Windows Update

The current user account if the update installation require UI to accept EULA;

Or Local System account otherwise.

AU App

This is for pre-Vista system.

This is when you go to Control Panel -> Automatic Update and set "download but let me choose when install"

The current user account
AU App with setting

This is for pre-Vista system.

This is when you go to Control Panel -> Automatic Update and set "install update automatically"

Local System account