Sadly, this came too late, but please try it.
It's based on the same AMDXHC driver for Windows XP, but this required just a device check patch.
Included are both 32-bit (x86) and 64-bit (x64) drivers, plus the "switch" driver.
- The AMDXHC driver is safe to use and easily installed.
- Supports all Intel USB 3.1 XHCI controllers (7, 8, 9, 100, 200 and 300 series, maybe even HEDT chipsets).
- "Switch" driver may be needed if you don't get USB3 speeds on Sandy Bridge, Ivy Bridge and Haswell (*) systems (7, 8 and 9 series chipsets). To use this, I'd recommend a backup.
Open Device Manager -> System Devices -> PCI Bus
Update driver -> Browse my computer for driver software -> Let me pick from a list of device drivers on my computer
Have Disk -> open the folder containing the HCSwitch driver files
PCI Bus will be displayed, continue the installation. When finished, just restart Vista.
(*) Haswell should work with Vista 32-bit (x86) only.
http://www.mediafire.com/file/1kjhhl0fq1ofc2m
The original Intel XHCI driver can be modded to work on Vista, but as this one works so fine, I don't have any plans to do it.