Crazy Eddie,
here's what you have overlooked in your solution of the three cards problem:
The RR card will always slide out red face up, the RW card will slide out red face up only in 50% of all cases. If you take that into account, you'll come to the 2/3 vs. 1/3 solution as well.

Your 50/50 solution would only be correct, if the RW card is only shown red face up. Well, this hasn't been explicitely excluded in Murray's post, but my reading of this post tells me that it was fairly obvious that each card could land on each side.

Marion, glad to help you here against Crazy Eddie, but I won't help you against his arguments in the prisoners problem. The way you have formulated it, Crazy Eddie is right.

Wolfgang