Some thought definanlty needs to be put into Anakin turning to the darkside. I can see why you might get rid of the "to save Padme" reason...and I can see why you would keep it. I think SilverKey and brash_stryker have both made good points.

I think what bugs me about the "to save Padme" reason is that when they meet up on Mustafar he's telling her he's turned to save her but then 2 seconds later he's talking about overthrowing the emperor and ruling the galaxy with her. It seems like in this scene (including the following scene with Obiwan) Lucas was trying to convey Anakin has gone "insane" for the darkside...which would work...but the problem is he's still using his reasoning skills. Does this makes sense the way I'm explaining it?

I think to make this scene with Anakin, Padme, and Obiwan work is to leave out the reasons why Anakin originally turned to the darkside. This would show that the darkside IS taking hold of Anakin...that's why Padme "doesn't know him anymore".

So I guess what I'm suggesting is to use the reasons given in the beginning of the film (distrust of Jedi and "to save Padme") and then by the time Anakin is on Mustafar he has become "drunk" from the power of the darkside so he has forgotten why he did turn in the first place. Make sense? Maybe? ;)