I would also recommend GT Legends for the PC. It costs about $10 right now, and you can drive a 914/6, 911RSR, 908 among many other awesome rides. Sounds and graphics are outstanding, car modeling and physics are top notch. I couldn't recommend this game more, especially for the giveaway price.
Read my review of the game here:
http://www.gamingheaven.net/gamingreviews.php?reviewid=353
rasta