xbox's are not xbox360's.
OP, Need For Speed: Shift 2 (titled Shift 2 in most places) is the closest thing to Forza on PC. Dirt 2 and 3 and Need For Speed: Hot Pursuit might be up your alley as well. I'd recommend a wheel for Shift 2, Dirt 2 and Dirt 3. I'd recommend a dual analog controller for Hot Pursuit.