There is no installation executable for these drivers, you'll have to install them manually via the device manager or through desktop properties. Right click on your desktop, select Properties, Settings, Advanced, Adapter, Properties, Driver Tab, Uninstall Driver button. I say uninstall driver rather than update driver as the 27.20s and a few other versions seem to retain your previous version's nvdesk.dll if you do not revert to the standard MS GF3 (GF2, whatever) first.
Upon rebooting you'll need to go through the same routine, but choose update driver rather than uninstall driver. Select "install from a list or location", "don't search, I will choose", then finally click the "Have disk" button and direct it to the folder you unzipped the 27.20s to. You're done.