Do not try to install it through Device Manager.
I just did mine less than an hour ago. So maybe this will help.
After reboot Windows 7 will load but have poor resolution. Go to where the Nvidia driver
is downloaded (mine was in the Download folder) double click the Nvidia driver download and follow the prompts to install.
It may show it did not install the driver but don't worry just reboot when it is finished installing or says it didn't install properly.
That is what mine did and after a reboot all was installed properly.
Also after reboot the Monitor will show in Device Manager.