Palps had Windu easy, he was faking it to fully convert Anakin to the dark side. Did you not see him annihilate the 3 masters only a few seconds prior to fighting Mace? Palpatine let the lightning deform him, so his arguement that the Jedi were evil and corrupt would hold much more weight in the senate. He has been planning this since Phantom Menace I believe, converting Anakin over that is. After Anakin chopped Mace's hand off, their isn't anything he could tell to the Jedi council that would save his ass. Palpatine set the bastard up ever since the beginning of the movie, by asking the council to put him on the council with rank of Master. He knew they wouldn't do that, which would make Anakin think they mistrust him. Pretty much anything that happens is because of Palpatine's plan to become Emperor.

So this baby seal walks into a club.