Looked at those Apple forums - they are full of people looking for the same answers. The £100 Dr Bott converter box is one of them which Apple sells. Just didn't work on my setup.

If I can make Windows work myself and have to go rootling around to find answers for a Mac... something's wrong, don't you think?

And you're right - don't even think of trying to run Windows, in Boot Camp or Parallels, on a MacBook Air. Won't be pleasant...