Personally I wouldn't bother, that's all I'm saying. Even if it does actually produce a difference, the hardware is the same, its going to be a few frames at best. What's the drivers for your card like on an Apple OS? Is it even supported? Last time I looked, they only support a few cards that they use in builds themselves.
Some fanboy will be in shortly to tell you that you should definately do it as not only will it improve your FPS, it will make your penis about 4 inches longer and when you boot up your machine in future a buxom lass in lingerie will materialise on your lap via the screen, and she'll be gagging for it like you've just bathed in Lynx, as the adverts suggest. (obviously she wouldn't be all over you if you actually bathed in Lynx as its pretty rank, there is some fine wenches in their TV ad's though...)