Pumping Iron with some circuit training. That is if you want to build muscle and keep your cardio up.
Insanity/P90x do NOT build muscle unless you are at the most basic level fitness wise.
I disagree about P90x. If you use a lot of weight, it will build muscle. You just have to work up to it and P90x is a great way to get there.
Don't believe me, ask the
experts:
That said, this research shows that P90X is a valuable way to burn calories, build muscle and improve your overall fitness level. “The data provides a lot of evidence to say that P90X does work,” says Woldt.
For more, google ACE and p90x.
Now, should you pay 150 bucks for the program, that is up to the user to decide. You could just as easily look online for free workout programs, and youtube videos and create your own similar workout programs, but p90x does provide an easy to use package. After some time, though, you may get board and need to move on.
As for Insanity, ACE has something to
say about that, too. No so positive:
Poor sequencing between body segments with inadequate anaerobic energy pathway recovery within same muscle groups (e.g., introduces push-up jacks and plank obliques at very end rather than interspersed between lower-extremity tests)
Begins with simpler, lower-intensity movements that induce fatigue before testing compound, complex movements later
Goodluck!
edit: another study, this one
negative on p90x and Crossfit from a military perspective.