Best Rudder Pedals

Is anyone using rudder pedals for a flight sim, such as Xplane or FlightGear?

I have a set that worked with my old PC, but not with my new iMac. In Xplane, for example, they seem to be making two inputs as if they were pedals for a a driving game. There is no switch on the to change this so I suspect they are basically hosed.

I am prepared to buy a new set, but am not sure what would be the best. I have heard good things about the CH Products brand, but have no experience with them.

Any tips greatly appreciated. And Yes, I love being back on a Mac. Other than this one thing, it has been perfect!