Ditto all of the above. It rules, and it takes a lot of time, more than most have. If you're pressed for time, I suggest the spartacus workouts Men's Health drew up. I've tweaked em quite a bit switching out exercises to customize it, but it's a good routine if you have less time.
http://www.menshealth.com/mhlists/hi...tine/

When I was in the depths of having no free time whatsoever with two kids in diapers (diaper stereo I called it) I bought Tony Horton's 10 minute workout DVDs. They were good because sometimes that's literally all I had was 10 minutes..and if I had 20 minutes, I'd do another workout.