I did 4 years in the Marines and used to hit the gym 3-4 days a week with 20 minutes of high intensity cardio followed by weight lifting.
Just recently though I started P90X and it's more intense than anything I ever did in the Marines or the gym on my own.
I downloaded P90X for free off of kickasstorrents.com and their manuals for the diet plan. It took a little figuring out and researching for the first few days once you get the hang of it it's easy peasy and works amazingly well.
Just a warning though you will be EXTREMELY sore your first week. As a regular gym guy and former Marine I went into the program thinking "Meh I'll be able to handle this no problem" boy was I wrong. I have to pause the dvd's every couple of reps because it's so intense.
After a few more weeks I'll probably have the workouts memorized by their titles and at that point I'm planning on converting the dvd to an mp3 so I can take it with me to the gym. It is nice working out in your living room but sometimes it's nice to be in the gym as well. Since I downloaded it for free all I had to do is buy the pull up bar for my door frame (20 bucks for the Gold's Gym one at Wal mart that works great also as a pushup bar if you want increased range of motion) and some dumbbells which were around 100 bucks at Wal Mart.
If you can handle the intensity and have the will power to stick to the diet plan I highly recommend P90X, it's like your own personal trainer but not everyone can withstand it. I know tons of people who quit only a few days in. My first week I could barely walk but I stuck with it. Hope that helps!