Grand Prix Legends (GPL) is the *BEST* GPL, IMO (and alot of other peoples
in here). It isnt exactly fun to drive, AT FIRST, but once you start to
get the hang of it, it is an awesome experience to race online with 19 other
drivers, a couple of metres apart. It will take you weeks / months to start
to get the hang of it, but perservere and you will have the best racing
experience on the PC.
F1 2001 is also very good, but lacks decent online support and Force
Feedback (as yet).
Rally Trophy is quite fun too.
Sports Car GT is good fun and there are 100's of new cars and tracks out
there to make it whatever game you like.
Hope this helps a bit :)
All the best,
Ash
DISCLAIMER : all the above statements are my opinion - no flamewars please
:)