I recommend you go straight to the 304.79 Beta with a clean install from Windows Safe Mode. Forget about the other versions.
Create a Windows System Restore Point prior to the installation. That way, if you encounter problems, you can easily undo the 304.79 Beta installation.
Then download 304.79, boot into Windows Safe Mode by pressing F8 at the ASUS splash screen. This will disable other running drivers (like Antivirus) that may interfere with the NVIDIA installation. Launch the NVIDIA installer, choose "Custom Install" and check the "Clean Install" checkbox. This will UNinstall your current NVIDIA driver prior to installation, giving you the best chance of driver installation success.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT