I'm actually the VistaBridge developer (or the main one, at any rate - there have been several contributors over the past several months that are adding content), and Sven speaketh the truth. The VistaBridge sample lib currently has very little fallback for
pre-Vista OS versions, and that is somewhat by design, at least in terms of our priorities around geting exposure to the new Vista APIs. I'm working on a version 1.1 (which really should be 0.9, but hey) that will be on my blog in "a while" that has a bit
more fallback behavior, but it won't be super-rich - 1.1 will have more feature work rather than revisiting what is there now, so don't expect miracles there.