Best Mac/PC driving sim with Nurburgring available?

[mft]

Can anyone advise? I've got a 2006 Mac Pro, which has good processor power, but the graphics card (an NVIDIA GeForce 7300 GT) is pretty long in the tooth.

So I'd like a good mid-range driving sim that will run on either OSX or Windows 7 (I'm all bootcamp'd up) which importantly has a good version of the Nurburgring.

Any suggestions?

[The Nur]

Cheap Xbox 360 and Forza? A new PS3 can be had with GT5 for <£200

[RobGT81]

Project cars?

[Altrezia]

rFactor / rFactor2 or netKar Pro.