New to graphic card plzz help?

If you put a 256 mb graphic card your total memory would be only 256mb...and all the above games would work for your pc confing with a 256mb graphic card.....its better if could have named your graphic card like if its nvidia 7 series or ATI radeon....Anyways there would be a problem if you are to play the latest games like Far Cry 2, GTA 4 etc.