Since this has segued into the actual argument, I suppose I better post my usual schpiel.
I am of the mind that Palpatine lost that battle only because he wanted to and because it would actually work better for him to lose than to win. Please examine the following. On their own, they are certainly not enough to decide one way or another, but taken together, they strongly suggest Palpatine threw the fight.
1) Look at how Palpatine fights. He leaps into the fray and cuts down three of the four Jedi masters in a matter of seconds. He moves so fast we can barely follow his movements. Then, once he's down to the last one (I.E. in no danger at all with the fight easily in his control) he visibly slows down. His swordplay seems to be more of a stalling action than trying to kill Mace. He even catches Mace with his guard down at one point and has his saber pointed directly at Windu's throat. If he was really trying to win the fight, he would have done so there. Two inches, one fight won. Instead, he backs off and they keep on going.
When he does go down, he only fires enough lightning to seriously deform himself (more on that later), and to hold off Mace. Then he suddenly goes limp and acts almost unconscious. This is a powerful image for Anakin, as it looks as if Palpatine is just a helpless old man about to be cut down by Windu. Additionally, why did Mace move to kill Palpatine in the first place? Because he fired the force lightning and brought it on himself. Before that, Mace was content simply to capture Palpatine but after that, Mace knew Palpatine needed to die. It was against the Jedi code and Palpatine looked completely helpless, but it put him in the ideal “victim” position. Then, as soon as Anakin leapt in and made his choice, Palpatine suddenly sprung back, even more full of life than he had been during the duel. Strong, strong evidence he was faking it.
And look at how he uses his lightning. When he first goes down against Mace, he shoots just enough to anchor Mace to the spot and to deform himself. Mace was clearly only just holding back the torrent of dark-side energy that was being unleashed against him. If Palpatine was going for the kill, why not up the ampage a little bit? He was clearly capable of doing more. When he kills Mace he uses a lot more lightning than what he’d been using on the ground. If he’d used that against Mace when Mace was standing over him, it is doubtful Mace could have held back that kind of energy.
2) Timing. The timing was perfect. Far too perfect for it to be purely coincidence. Anakin comes in at the precise moment that Mace is moving towards Palpatine and holding a saber at his throat. He is treated to a scene straight out of a horror movie. The only man who has ever shown him any sort of real approval, compassion and encouragement, the only family he really had outside the Jedi temple, the only father figure he would ever know and the only person who has showed any interest of even HELPING Anakin to save Padme is being held at saberpoint by the leader of the Jedi council. Mace is breaking both the laws of the Republic and the Jedi code, yet seems not to care on both counts. That is a powerful image that likely tipped Anakin over the edge.
Consider what would have happened if Anakin had arrived earlier or later. If he arrived earlier, he would witness that same man I just described as a tempest of rage and destruction. He would see this man off three Jedi Masters, then try to kill his master and, worse, he would be there to witness him win or lose the lightsaber duel with Mace. Neither is a good situation. If Palpatine wins, Anakin realises this kindly old man whom he had looked up to like a grandfather is actually a psychotic murderer, but if he loses (at what is essentially a fair fight) he seems too weak to be of any help to Anakin in saving Padme.
Now what if he comes in later. It doesn't have to be much later, it can even be 10 seconds later. He will be treated to one of three situations (excuse my excessive use of flow charts)
i) If he arrives only a few seconds later than he did, he will not see an old man begging for mercy at the hands of a fierce warrior, he will see Palpatine defending himself with a torrent of force lightning. It is nowhere near as shocking an image and once again promotes the idea that Palpatine is a murderer, not a helpless old man.
ii) If he arrives later than that and Palpatine DID throw the fight, he will see that kindly elderly gentleman standing over the corpses of four Jedi. No sign that Palpatine was ever in the right or defending himself, no helpless image. The rage alone of losing even more of his friends and allies might force Anakin to attack Palpatine and there goes his new apprentice...
iii) If he arrives later than that and Palpatine DIDN'T throw the fight, Palpatine is now dead. That doesn't really help him in his quest for galactic domination much.
My point is that Anakin arrived at the perfect time down to within a few seconds to be confronted not by a scene that paints Palpatine as a butcher or a warrior, but as a helpless old man. It is not inconceivable for Palpatine to have thrown the fight at that very second. As someone pointed out, he can sense Anakin's pain when he's on a totally different star system millions of mile away. He can talk to him across a city. Is it not, therefore, logical to say that he could probably sense him coming up the stairs?
3) Motivation. Palpatine knew the Jedi were coming and they would arrest or kill him when they got there. He knew it when Anakin said he was going to turn him in, he knew it when he was talking to Anakin telepathically... so why stay and fight? The Jedi needed to be cut down, true, but why not just leave work a little early, issue order 66 from the safety of an escape pod and let the clones do the dirty work when the Jedi arrive at an empty office? No, he needed to be there because THAT would be the point where Anakin was weakest, where he would be forced to choose a side: Palpatine and, by extension, Padme, the only people who had shown him affection and encouragement, or the Jedi, who were willing to let his wife die. Palpatine knew that if he was in danger, Anakin would need to save him and that would be his final undoing.
Palpatine even knew that violence was going to be there. He knew the Jedi would try and kill him and he planted that idea in Anakin's head. "If I die, any chance of saving your wife dies with me." He already told Anakin that violence would erupt and the Jedi would attempt to take his life. Does that not indicate at least SOME level of forethought?
If you truly believe that Palpatine DIDN'T plan the whole thing in advance, then ask yourself, "Why did Palpatine stay?" When he knew the Jedi were coming and he knew what they intended to do to him, what possible reason is there for him to stay at that office and not run or relocate? There is absolutely NOTHING for him to gain from that fight aside from Anakin. Palpatine is the dark side's king of the Star Wars chess board. If he died there, or was captured, decades of planning would go up in smoke just like that. Palpatine, being a tactician, knew this better than anyone. He wouldn't risk death or capture if there wasn't a seriously lucrative potential gain on the table. Like, say, the Chosen One as a new apprentice, ushering in a new golden age for the Sith.
4) Gain. Palpatine gained EVERYTHING from that fight. Four Jedi Masters dead, the most powerful Jedi in the galaxy turned to the dark side, a new set of deformities that allowed him to wrap himself in a flag and have physical evidence that the Jedi were senseless butchers... He made out like a bandit. You just don't get fights to work out THAT perfectly for you unless you've put a lot of planning into them.
Think about that for a second: with that fight Palpatine kills two birds with one stone. Not only does he turn Anakin to the dark side, he suddenly has ammo for his crusade against the Jedi. If he goes into the senate covered in hideous disfigurements that he received during a Jedi "attack" on his office, no one will be able to stand up to him and say, "But the Jedi are good, honest people." Palpatine made himself into living evidence of the Jedi's evil and used this leverage to justify his attack against the Jedi.
The Clone Wars were about to end and Palpatine HAD to play his hand. If that fight truly wasn't planned and Palpatine didn't intend to lose, why bother having it at all? He has everything to lose and nothing to gain from doing so. Order 66 was about to be issued anyways (again, due to the end of the war)... why not just leave the Jedi to the clones? Instead Palpatine risks his own neck... that right there suggests he knew all along what he was doing.
So there you have it: Four very good reasons why Palpatine threw the fight. Are all these just some huge cooincidence? Did Palpatine just get extraordinarily lucky? Perhaps... but in my experience, there's no such thing as luck. Especially when four Jedi Masters, the Chosen One, a Sith Lord and the fate of the galaxy is involved.
Last time I checked my thesaurus, "old" and "powerful" weren't synonyms.
