I just bought rFactor for the PC, and I have to say its a damn good game.Aside from the fact that it ships with less cars and tracks then GT4, it has it beat in every way. The feeling of the cars is so good, and the tuning is simply rediculous.
From tire pressure, to brake rotor thickness, you can tune the **** out of these cars.On top of that they have basic sliders such as "oversteer-understeer" automaticaly re-shape the cars tune for people who don't quite understand the differences in settings slow and fast rebound settings...
The free demo is avalible at
http://www.rfactor.net/If you buy it make sure to check out
http://www.rfactorcentral.com/ for all kinds of cars and tracks to add on to the game....(some one even made the top gear test track, though its a work in progress and currently looks like crap)
If you have a logitec wheel for you play station you should be able to plug that into the usb of your computer just fine, its what I'm using.
http://www.youtube.com/watch?v=pIa9A3lHmEg
If anyone has this, or gets it let me, and we will set up some races