New Linux Ubuntu user here.
I have a GTX 660 newly installed. I am currently working on updating the default Nouveau drivers to NVidia provided ones.
This link has been helpful:
https://help.ubuntu.com/community/BinaryDriverHowto/Nvidia#Problems_with_Video_Playback
Does the card work with the Ubuntu provided drivers? Yes and no. As for the desktop interface including internet folders etc. yeah there was an instant increase in resolution once I installed the Video Card. However, when I went to play a game, it was incredibly choppy. The default driver (Nouveau) provides lower frame rates for many of the 3D acceleration tasks games require. I'm kind of a noob I don't know, but I hope this helps.
In conclusion, if you're going to get a GTX 660 with Ubuntu, and want to play games (especially newer games), I believe you are going to want to install the proprietary nVidia driver.