[gcheong]

There is no amount of preparation that will prepare you 100% and guarantee you a job at any of these companies. I think we've gotten to a ridiculous point with the interview process now and at some point you just have to decide you've done enough to prepare on the technical end and it sounds like you're basically there. I would probably start looking at other aspects of preparation. Think about the human aspect of things and what you want to impress upon your interviewer. These are more subtle things that might make the difference when deciding a thumbs up or thumbs down. But in the end don't sweat it. Decide you're going to have fun with it and see what happens. Truly try to enjoy yourself and view each problem as an interesting puzzle instead of some do or die test. And hey, free lunch!