Somehow, windows seems to think that a driver for another device is a valid update for it, maybe that specific hwid slip into the compatible devices list for the driver.Finally last month I got to solve this though I didn't take note of the steps I took (I didn't think it'd work) so I cannot post a reliable answer to this question.But Windows show two driver updates in Windows Update: an update to the Intel integrated graphics and an update to the SATA AHCI.
Automatic updating of drivers device
Edit: Just in case anyone wonders, disabling the device in the device manager won't change the outcome.
Update (28/02/2014): The new version of the bootcamp drivers which officially support windows 8.1 still give me this problem, both updating and installing from scratch.
All I can recall is that I did have to update the driver and uninstall it afterwards, maybe booting in safe-mode. It's a shame, all of my other Macs updated flawlessly, but this one, precisely the one I use the most, is giving me headaches.
Just so anyone coming here knows: To this day I haven't found a solution to this, I'll probably have to wait until Apple decides to release updated Boot Camp Drivers.
That's if I haven't sold it when the time comes...