I purchased a 670 two days ago and it will be here on Wednesday. I currently have a 6970, but I will be giving it to my brother so he can XFire. (graduation gift ). I've purchased 3 other cards in the past, all AMD. So, my question is do a lot of people invest in a separate card to run PhysX? Do a lot of games use it? And if it would be worth it to me, what cards should I look at?