First please boot into Normal Mode, right click on blank area (if available), choose View --- Show desktop icons.
If we cannot do the right click, please start Task Manager, check if Explorer.exe is listed in Processes tab.
If not, click File --- New Task, input "explorer.exe" and click OK to see if this can bring the desktop back. AFTER trying this and if you still see the desktop blank try the step's below
1. Boot that bad boy in Safe Mode
2. Click on Run then Control Panel
3. Open System then click on Device Manager
4. Expand the Display Adapters Tree
5. Right click on the second “NVIDIA GeForce 7950 GX2 (Microsoft Corporate – WDDM) entry and select Disable (click yes on the pop up)
6. Right click on the first “NVIDIA GeForce 7950 GX2 (Microsoft Corporate – WDDM) entry and select Uninstall. Click on OK when asked.
7. Restart the Machine.
8. Let the PC boot normally (not in safe mode)
9. Windows will automatically install the default driver and re enable the second card. It’ll then ask to restart – DON’T – Click Restart Later, click on "Restart Now
10. Head on over to http://www.nvidia.com
and download the Windows 7 Drivers for the 7 Series GPU (version 185.81 beta is the current version at time of writing clocking in at 97.9mB) – Save it to a location that you can access in safe mode (not network drives. Desktop is a nice easy place)
11. Now that you have downloaded you will need to reboot back into safe mode (the Nvidia drivers won’t install because there is a previous installation that requires a restart… Thanks to Windows.
12. Once rebooted, run the Nvidia installation.
If you check the Display Adapters in Device manager after the installation you will see that it’ll just list “NVIDIA GeForce 7950 GX2″
13. Reboot again (normal boot this time, not safe mode) and if all went well you should now have your Windows 7 Desktop all up and running pretty like.
I believe this is the best way of installing these drivers but I just know that it work's fine..