More than likely, it's not running PostSetup.dll(within WebAppBuilder) because of an error message. You may want search for the ActiveVFP messages today and in the past for some info on this. For whatever reason, it seems to be a problem on XP....
>Progress report - the vd's are not registering in iis - if I create them manually the app works as expected (far as I can tell). Have been looking at the app source code. More later.