[Zope] External Editor on Client?

Hi, I've got an intranet app that uses Plone, CMFTypes and Word so that using the joys of External Editor people can happily edit and save Word docs oh so easily. But I need to be able to tell if the client has EE on it and if it doesnt display a warning message that points them to the download page. Anyone got a cunning way of doing this? There's nothing in the HTTP headers (on my IE and Mozilla anyway). I could add a sort of ping to External Editor that returned its version info, but that would just be a "download this file?" dialog in most browsers and not something useful. Any other ideas? -- Andy McKay