You can try extracting the installer with a utility like
7zip or
WinRAR (navigate to the WinRAR x64 3.91 down the page, though it says trial it never stops working). Once either program is installed you right click the installer and choose the appropriate extract option.
Once the contents are extracted use device manager, locate your video card driver, double click it then choose to update the driver. Choose to find the driver rather than an automatic search. Browse to the folder you created and click OK on the sub folder containing your driver. Then click through the prompts to finish the install. It will either give you a message that it could not find a driver or that it was successful.
Sorry I can not be more detailed but I am on my Macbook at the moment so do not have access to the direct prompts on my Win 7 desktop.
Edit: I forgot for a moment but you should be able to skip the WinRAR steps. When you run the nVidia installer it extracts all the driver file to a folder labeled NVIDIA on the root directory of your C: drive. Just browse there when installing manually through device manager.
I also try to install all drivers through device manager. So that I can avoid the junk programs that get installed alongside the drivers. This is really useful for Wireless cards as the third party managers do a horrible job maintaining connections compared to Windows built in Wireless Zero Config service. As a bonus most drivers can be installed without a reboot. NVidia is a notable exception but ATI drivers work great this way.
After the install I would go to RUN > MSCONFIG and disable all nVidia services and startup items that get added. They add nothing to game performance but do a great job of hogging resources and increasing boot time. While your at it disable reader sl, quicktime and most other startup items. Be careful with services though click the checkbox to hide Microsoft services and you can screw up functionality if you disable the wrong one.
