I've done P90X and I love it. P90X is a tough 13 week program. Power 90 doesn't come even close since X is not meant for beginners. There is a fitness test on the web site, or there was a few years ago when I first bought it.
It does use a lot of bodyweight exercises such as many pullups and pushups in every conceivble variation with most of the other exercises using dumbbells. You will probably want some sort of pull up bar, though they show variations with bands. There is not a lot of cardio.
The program is split with chest/back, shoulders/arms, legs/back, yoga, a plyo based cardio/leg, kickboxing and a stretch. After 4 weeks the split changes to back/biceps and chest/shoulders/triceps for 4 weeks and then alternates the last 4 weeks. There is also a tough abs workout and a "functional fitness/core" workout. Most of the workouts clocked in at about 45 minutes, although the yoga was 90 minutes and most days you tacked on the 15 minutes of abs.
The recommended routine is 6 days a week including the plyo, yoga and kenpo. The stretch is for the off day. I really enjoy this program, but you might check videofitness.com for more thorough reviews detailing what many people like and dislike about the program.
The nutrition plan goes from low carb to higher carb. I didn't follow this plan, just mainly ate normal and I still saw great results.
Tony Horton is an engaging personality, although some find him a bit over the top. He's easy on the eyes

as are a lot of his back up exercisers with out being like models. More like really fit next door types. The kind you'd love to live next door to types. Not that that will help you get a 6 pack, unless it inspires you to work out more

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I had my fourth child a year and half ago and followed P90X last year and it helped me lose 20 lbs., although I think it is more of a get you from okay shape to great shape, not primarily weight loss. I was in great shape before I got pregnant after doing a couple of rounds. Though now I still have a ways to go to be back in great shape.
Right now I'm doing NROLFW (which I started in Jan. and am currently in stage 4) because I believe in changing things up. I can't decide if I will do P90X or Afterburn next, but I plan to do another round of the X before the end of the year. Hope this helps.
Again, the reviews at videofitness.com may really help you out.