How to check that both graphics cards are working

[Chef Necro]

Hi I was wondering how to find out if both of my graphics are working together, they are in the s1 formation (I believe that is what it is called) This has only become an issue as after installing a new game (modern Warfare 2) I found that my computer's graphics cards should be more than enough as one individually is more than the recommended but it is black screen until i try to go back to desktop, then in game on one of the levels it cut parts of people off up to the point that there was floating hair, and after the game didnt move on.
Is this a bug in the game or a problem with my graphics cards?

 

[wa1]

U can download software called GPU-Z, i got it from www.techpowerup.com
that software will tell u anything about your card(s)...