Fake fight all right. Considering how easily Sidious slaughtered the other 3 council members, he could have killed Windu just as easily. He had the chance to stab him right through his chest, but he didn't do that.
DarthSeverus: he could see the future (Yoda said in Ep. II that only those who turn to the dark side could see the future if the darkness grew), so it is a very strong possibility that he said those lines on purpose.