I played both and GT5P has way better lightning than Forza 3.
For the rest, Forza 3 beats GT5P.. but it is only prologue...
The important thing is the fact that Forza is a younger franchise than Gran Turismo... and they are very close to each other now...
Evan Wells (Uncharted 2): I think the differences that you see between any two games has much more to do with the developer than whether it’s on the Xbox or PS3.