Windows 7 probably has a newer version included than that Vista driver
, that or it may have been installed through Windows Update.
By the way did you remember to disable the onboard video after installing the new card? If not with it being an AMD card not only will the onboard still be active, but there is another option in the bios under,
Advanced - Chipset - 890GX Configuration - Internal Video Configuration
called Surround View (that defaults to auto), that allows for the use of the onboard as well as the video card for extra display connections (it does get disabled when the onboard is set to disabled).