Use MultiMiner.
It's a GUI front end for BFGminer it automatically detects all of your cards. You can put arguments in a further box specifically for scypt mining to maximize your output.
https://bitcointalk.org/index.php?topic=248173.0mining with Two GPUs, ATI HD7950+Nvidia,Driver for nvidia already working, u use this PC for gaming too, so the second card is now for Hybrid PhysX, its working, 100%, but how do u use both cards to mine...
i use cgminer...only cgminer....
Anyone know how?