The nice thing about MMO's is that you can remap the keys. I do that with everything I play, the moment I log into the game for the first time. So I never have any trouble remembering which button does what.

What I have trouble with is remembering what ability does what. Not only do I have a tendency to rotate between two or three MMO's, but I also have bad altitis. Trying to remember how the different powers work together can get a little hairy at times!