FYI - I got the following response from Philips in an e-mail.
Dear Mr Griffith,
Unfortunately it is possible that no official support for Vista will come for the
ProntoNG series. While drivers should work with Vista by default as it is an USB
device and the software should also work, we cannot promise that it will or provide
any proper support regarding it either. We're very sorry for the inconvenience.
We hope we answered your question satisfactorily.
With kindest regards,
Philips Customer Care Center
Luckily for those of us with the older remotes the workaround seems to work just fine.