I just ordered a new dell studio desktop and i want to find out how well it will run certain demanding games?

You will be able to play Crysis fairly well with that setup, and you will be able to max out The Witcher easily. My setup is an dual core 2.6GHz, 4gb DDR2 800 RAM, 8800 GT, Vista Ultimate and can play Crysis on everything medium with 2xAA and can max out Witcher.