In Vista this algorithm was extended to include eight levels of digital signing:
This behavior is illustrated in setupapi.dev.log when determining which driver to install for a device. Further considerations for which version of a driver should be installed for a particular device is:
(Note: Date and Version are only considered if every other aspect of the driver rank is equal. Setup assigns the best signature score (lowest signature score value) to drivers that have a Microsoft signature for Windows Vista. All Microsoft signatures are assigned this best signature score. All else being equal in a driver rank, Setup will select the driver that is the best match from among those that have a Microsoft signature for Windows Vista.)
Knowing these algorithms can help you troubleshoot device driver issues regardless of how the driver was installed (i.e. in-box, third party). The best source of data for which driver was chosen as the "best match" is by reading the setupapi.dev.log file.
A good article on troubleshooting using the setupapi.dev.log can be found here:http://download.microsoft.com/download/e/b/a/eba1050f-a31d-436b-9281-92cdfeae4b45/SetupAPILog.doc
Best Regards,Chris Taylor