Monitor refresh rate is not affected by what type of gaming your doing. If your gaming in 2D or 3D, regardless, it will refresh at 120Hz always. It also smooths out movies, but is not always preferred by some who enjoy the movie for what it already was, some movies we're meant to have stuttering. If you want a little more information, try visiting this link: http://reviews.cnet.com/4520-6449_7-6792632-1.html
It was written quite awhile back, when the new technology was just hitting the shelves, but none the less it still provides useful information for your situation.