Which OS are you using?
Windows XP allows you to create different hardware profiles. http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/hardware_profiles_overview.mspx?mfr=true
^ This may resolve your issue (if you run Win XP). It was originally intended for laptops, but found many uses for desktops as well.
However, Windows Vista/7 did away with this feature.
Correct me if I'm wrong, but I thought that the Nvidia Control Panel allowed you to choose which GPU to run whichever application. I did this with my previous laptop. I was able to choose between the Intel on-board or the Nvidia Quadro 4200M for a specific application, or globally. This way you could point your office/work applications to the Quadro GPU, and the gaming apps to the "gaming" GPU.