This is almost half as much as Windows XP which shipped with 10,000 drivers included on the CD five years ago, and an additional 2,000 available online.
But even with all of the drivers being provided by Microsoft on the install DVD and through Windows Update, it's still up to the device manufacturers to make sure that they get updated software out to customers who make the Vista upgrade. The official Windows Vista newsgroups are still littered with testers having issues with failing drivers or no driver support at all for numerous peripherals.