TPA Sun-
Well I don't know your circumstances but you might be surprised at how accessible P90X is! There are some people who were very big to start and then lost a ton of weight thanks to P90X and a good diet. If you look on the net for P90X success stories, look specifically at Richard Neal, Tommy Mygrant and Jeremy Yost because they were all very big and lost a lot of weight but more to the point they are ripped now and healthy. I modify the moves to compensate for not being that fit and for being overweight, and that's the nice thing about the program is they show modifications that people can use.
Insanity, on the other hand...I did almost a full round of it but it just trashed my knees. I'm still too big to be jumping around like that. Maybe I'll try it again after I lose some more weight. Who knows, maybe I just have weak knees. It seems like there are tons of people who succeed on that program as well, but it wasn't for me. Yet.
Dee