Following any regime or program involving strict exercise and diet will net positive results. I'm not really formiliar with this p90x program, but I can tell you that I don't do 75% of the workouts that are included in the DVD's I saw. Theres a lot of non-functional workouts targeting beach muscle, and I personally think this is an inefficient method to train. You should focus on being really healthy and not looking good. Plenty of body builders die in their 40's-50's.
Right now I'm not doing anything myself but go to bjj, but when I work out on top of that I normally do
http://www.crossfit.com/ which was refered to my be Murd. This was a popular workout routine in prison among in-mates, so you know it works!
Anyway that daily blog gives you a workout every day that will turn you into a machine. You would be able to outwork any of the big muscly beach fags in those dvd's any day of the week after 7-8 weeks of training. Seriously.
You can also find crossfit clubs in your area which have their own custom workouts. They have personal trainers that can help you get much better results. My personally suggestion would be to find a submission wrestling, grappling, or jiu-jitsu club. Replace all your running with grappling and your belly will instantly disapear without adding any additional workouts to your week. Then anything you do on top is just making you better, faster, stronger.
P.S.- some of the plyometrics stuff looks cool in the dvd's. I'm going to download them now and add them to my collection.
