I would agree with what Rex4998 and Ron Burgandy have said.
P90X is great for beginners because most people (men and women) are intimidated by the gym atmosphere at first. This will put you in your own home and produce results, as long as you follow a sensible diet.
I would say this program is going to help you get started, see some results, and motoviate you to take it the next level. Keep in mind that at some point, this program will not be difficult anymore. Our bodies are highly adaptive so that's why they change the movements up so much. The problem is, it's the intensity that and workload our bodies adapt to so this program will only work for so long.
I would highly recommend anyone on a workout program create an account on
http://www.fitday.com. This will track your calories for you and tell you exactly how much you are eating.
The most basic diet you can follow is:
1. Don't drink your calories (sodas, tea w/sugar, etc.)
2. Cut out the junk (candy, chips, fast food)
3. Time your carbs - try to eat your complex carbs in the morning to mid day. Don't eat them at night
4. Don't cut out all fats; fat is needed
5. Getting a hamburger and french fries, but with a diet coke doesn't count as dieting
6. starving yourself all day and then gorging at night will not work