Without Rondo, the Celtics are NOT better than the Knicks.
The Knicks are a really good team. They had a rough stretch in the middle of the season (of course they did, with Sheed there to tell them when to flip the switch), but at the beginning and the end of the season they have been VERY good. They have the best defensive big man in the game, and one of the top 4 or 5 isolation scorers, which is the makings of a very good playoff team. Add to that the depth and veteran toughness they have this season, and I think they are going to be a hard out for even the Heat, if they can stay relatively healthy.
The C's on the other hand, are missing their best player (arguably), are very thin up front, and have no one who can break down defenses, and create shots when the defense tightens up.