The Logitech PS2 wheel does indeed work - I've got a Driving Force (not Pro) and I use it on my PC with no problems at all.
In my opinion, the best sim out there is LiveForSpeed, extremely realistic physics. The downside is that there are no "real life" cars or circuits, however the cars that are included do a pretty good job of representing real equivalents, and the circuits are well designed. No mods available at the moment though. Well worth the 24 quid
rFactor is another good option, with many mods for real life cars and circuits, the best place to get the mods from is rfactorcentral.com. As already mentioned, all the mods are free to download.
With regard to the original topic of this thread, there are already 2 or 3 Le Mans circuit mods available for rFactor, so you can go driving there, albeit not in a Group C car just yet.