For those having issues installing drivers that are not digitally signed, but still want to use the driver: here’s a way to disable enforced driver signing.
1. Go to Start | Run | Type gpedit.msc, and click OK
2. Go to User Configuration | Administrative Templates | System | Driver Installation
3. Select Code signing for device drivers | Properties | Enable | Ignore
Reboot, and you should be able to install those drivers with no more problems