My new fix is Forza Motorsport for XBox. I am really getting into it. I particularly like how you can search for cars that match certain criteria; searching is a feature that is common to most applications (be it web, windows, whatever) but not so much in games... I'd like to see more of this.
Also, I REALLY like the fact that they licensed Porsche and Ferrari, these were missing from Gran Turismo 3 and it was disappointing (yes, I know that RUF's cars are really Porsches, but still)
I haven't yet played GT4 and was wondering how it stacks up against Forza.... I have a PS2, so I might pick it up if it's better than Forza.