GT5 is probably more realistic than Forza Motorsport or NFS,which are really arcade games.
Here is video
If you have fast PC try download LFS(Life For Speed),which is most realistic game with rFactor,but for full benefit and potential i would recommend play with nice steering wheel such as Logitech G25(this only work with PC or PS3,not working with Xbox 360)
Here is video from rFactor
Jura