well
here is what you need minimum:
CPU: Core 2 Duo E8200 2.66GHz or Phenom II X2 545
GPU: GeForce GT 530
RAM: 4GB
Here is what is recommended ( that won't be ultra mind you, most likely high )
CPU Core i5-2500T 2.3GHz or Phenom II X4 975
GPU: GeForce GTX 480 or Radeon HD 6970
RAM: 6GB
So you can run the game, but forget ultra unless you want to play - freeze - play ( and in the freeze time you drove through 3 streets, killed 7 people and pissed off 12 cops - freeze - crash and burn