This is how I installed my drivers from now on and I have had no problems whatsoever...
I download the latest drivers for my Video, Audio & Monitor and save it to a Folder I can get to later.
I uninstall my current driver from Device Manager, I immediately see the screen changing to regular vga drivers, it asks me to reinstall, I DO NOT do so, I know go to the Control Panel and uninstall the PhysX drivers as well (this is part of the 170/180/190 Nvidia series drivers), I Reboot now and Vista installs the std vga drivers, I then use CCcleaner to get rid of any instances or drivers remnants on my registry (when you open it, you'll see the registry icon, choose it and Run it. I reboot again for good measure.
Once I am back at the desktop, I go to the folder where I downloaded the drivers, un-compress the file directly to the same folder I saved it to, I again go to my device manager, go to my display adapters, double click on vga card and then, double click on driver tab and click on update drivers.
Once there, I tell it to let me choose the driver, click on "Have Disk", search for the folder where I uncompressed the executable and click on the .inf file, it starts doing the whole installation process and tells me to reboot once its done.
I am sure there are other ways to do this faster but, so far, this has work for me in Vista x64... I wouldn't think it wouldn't hurt anything trying it this way.
If this fails, we will use the other method.