This is my second go around with P90X and IT WORKS!!! I got mine on ebay for $75.
The first go around I followed the 1500 calorie diet plan in the book and still got results, but not as much as I wanted. This go around (I finish on April 24, 2010), I am using a different diet that is 1100 calories and am seeing much better results. You are what you eat!!! Its SO important to eat right when your doing this workout program. Eating right will give you the energy you need and let you lose the weight you want to at the same time!!
I am doing it with a friend to, we work out everyday after work. I can't tell you how many times I wanted to give up, but because I had her support, I felt like I owed it to her to stick with it.
Good luck with your goals!!!