GTR2 /GTR Evolution and Live for Speed continue to be the ones I like but there may be newer options now, my gaming PC broke a year ago and I haven't kept up with things since. http://www.lfs.net/
Ok I'll have a look at those. Just had a little browse on the Game store. There's one called Race Driver:GRID which looks pretty good. Outrun 2006 also has a good review. Not a big fan of the NFS series.
GRID is awesome.
If you want a more realistic racing game though as mentioned GTR-Evolution,Race 07 and xfactor are the ones to go for. They have many tracks including the full nurburgring and you can download loads of extras like F1 cars and tracks and even the topgear test track.
I use my PS3 GT wheel with the PC.