I'm waiting for Forza too. Tried the demo and I liked it. It did feel a little more real than the GT games (I haven't played GT4 enough to make too many comments about that one though.).
When it comes to realism in driving games, you just can't beat GTR (
GTR — FIA GT Racing Game). Unless you actually have a proper racing license there's no way you can play the "simulation" setting successfully. Even semi-pro is extremly difficult at first, but after a while you start to get rid of years of videogame arcade behavior and can actually start to get some decent laptimes. :-D
