No, they also work with the Gainward.
Just like the Detonator drivers, which are unified for all models, so is the WDM driver.
It does contain information specific for the Personal Cinema, but also installs the general WDM drivers.
Anyway as I mentioned above you can also get them at Gainward's site.
I personally used the drivers from NVidia page, and they work, but I don't know if there is any difference between them. In any case you would probably be better off using the ones on Gainward's site.