Short answer: 3D games should never run on a MacBook. It will make you cry.
Long answer: Sort of. If you can get a free demo of a game with the game engine and most game features in tact, try it before you buy it. Running a full game takes a lot more out of a system than a minor feature set demo. Better safe than sorry.
Why my opinion doesn't count: I am running the GMA 950 MacBook. So my experience doesn't directly transfer to newer models.
Why you should think twice anyway: Intel is notorious for crappy integrated graphics solutions across the board. But at least the X3100 will give a shot at 3D; In EVE (which has the disadvantage of being Cider ported) my MacBook just sort of sits there laughing at me with random in-game icons, viewing windows, and misplaced textures strewn about the screen, all at a blazing .3FPS. It is very pretty to watch, but oh so painful. It's like a bad techno-acid trip of some sort.