How to Tell which graphics cards are better than others?

I've seen many graphics cards that are only 1 gb that are way better than most 2 gb graphics cards. That doesn't really make sense to me. What should I look for in the specs of a graphics card to tell if it is good enough to run even minecraft on at least 60 fps.

Guest

You need to look at the number of cores/stream processors. This will be the biggest factor in pure performance. But when newer cards comes newer features. So you may have an older, more powerful card that actually doesn't perform as well as a newer, less powerful card. How do you tell which card is better? Watch benchmark reviews. That's the best way.

Kevin