About a year ago, our boss started pimping his Crossfit routine. He said that P90x just couldn't compare and it eventually turned into a full blown competition between guys using P90, Crossfit, and Insanity. There were no official results (because nobody would volunteer to judge...or to model), but in my opinion, P90 gave the best results (from a pure vanity viewpoint). I used P90 for awhile, but it was just too time intensive so I've since gone back to a more normal weights/calisthenics routine. Insanity was just brutal. Without exception, all of the guys that started it flamed out.
Crossfit has a lot going for it, though. There is not a single person in my workplace that can keep up with the old man.
Anyway, good luck with the P90x. I've never been so sore as I was the first two weeks. It got easier quickly though (except for that plyometrics bullshit...god, I hated that) and you see and feel results very quickly.