I just installed prototype and game runs sloooooooooooooooooooooooooooooooooooooooooow

My sys:

AMD quad 2.3ghz

nvidia 8600 on 512mb ddr3

3 gig RAM on 667MHz

vista ultimate

even if i put graphic to lowest setting still runs very slow like slow motion

Any sugestion to inprove this we all need to buy INtel i7 CPU