A few days later, however, Anakin learns that Palpatine is a Sith lord, and only through the dark side can he learn how to save Padme. At this point Anakin should have thought, "Wow. He's a Sith lord. That means everything, EVERYTHING, he's said since I first met him was a lie. I guess the Jedi Council was right." But he doesn't.

When Mace Windu and the other Jedi go to confront Palpatine, Anakin is left alone with his thoughts. He thinks he must choose between being a Jedi and losing Padme or turning to the dark side and saving Padme. But when he decides to go to Palpatine's office, I don't think he had chosen the dark side...yet. I think he went to ensure that Palpatine was just taken prisoner (as opposed to being killed on the spot) so that Anakin could at least learn how to save Padme while still being a Jedi. However, when he sees that Mace is going to kill Palpatine, Anakin chooses to stop him. His choice leads to the death of Mace Windu. Now, I still don't feel Anakin has turned quite yet. As soon as he realizes that he brought about the death of one of the greatest Jedi in the Order, he says, "What have I done?!" I think he then realizes that if he faces up to what he's done, he would be severely punished by the Jedi. Now is when he makes the choice. He can either take his punishment and (in his mind) lose Padme, or turn to the dark side, not receive any punishment, and become so powerful that he could save Padme. Now is when he turns to the dark side. He knows it's wrong, but it's the only way to save Padme, so to him that justifies his choice (cookies over carrots). He chooses the quick and easy path.

However, I don't think he even had Padme's interest in mind when trying to save her. I think the root of his desire to keep her from dying was saving himself from his own pain. When his mother died, he felt terrible, terrible pain. He loved Padme just as much as, maybe more than, he loved his mother, so losing her would make him experience that terrible pain again. Shielding himself from that kind of suffering was his real reason for wanting to save her.

After that, it's all downhill. His atrocities build on themselves until he becomes impervious to any feelings of remorse. By the time he confronts Padme and Obi-Wan, he's so seeped in the dark side that he no longer cares about anyone else, even Padme.

It could have been painful to watch Anakin make all of these decisions and slowly become the monster that is Darth Vader. But thanks to the master, George Lucas, Revenge of the Sith is a pleasure to watch over and over again.