Marvelharvey knows his stuff, for sure. One of the most fun times i had with Forza 2 was with the hot laps. He critiqued my laps for a few of them, and gave me detailed breakdowns of braking points, the line I was using etc. I took massive chunks of my times thanks to that, though I never got close to his

. If he says GT5 is better, I'm prepared to believe it.
About the physics: I have no idea technically what's going on under the hood with Forza but it feels more convincing than anything else I've played (disclaimer: haven't played any of the beardy PC stuff). What a lot of console racer fans don't get is that driving in Forza is intuitive, not cerebral. You can feel the car, feel how it contacts the track and feel when it loses contact. You don't need to know what pressure your tires are at or how hot they are to know when you're going to lose traction on a hairpin.
DC - if you want to check it out in 1080p, you can always bring yer PS3 over to my place one of these days!