I think that it's a good thing to make a backup using Time Machine before proceeding in this tutorial. If you want to give it a try, remember to make a backup of your system before. PERHAPS, this tutorial can also work with ATI cards. OBS³: In the software I used to generate the EFI string for my card (OSX86Tools), there are some ATI cards listed.
OBS²: I don't know if this tutorial works under Mountain Lion (10.8), so if you want to try, don't blame me if you get any kind of problem, try it at your own risk! You just have to download the right system version of the nVidia driver. OBS¹: My experience was under the version 10.7.4, but I think the method described in this tutorial works under 10.7.3 too. Install the Mac OS X Combo Update 10.7.4
After a lot of research, I got my video card working and decided to share my experience.
In my case, after installation, my screen was turning off during the start, just after the loading gray screen with the Apple logo. This method is for the ones who didn't get their video cards working properly after installing (normally) the official nVidia driver. Building a CustoMac Hackintosh: Buyer's Guide
