Yourself! Fitness is actually a great program, in my opinion.
The model demonstrates the exercises for you, and adjusts the level of difficulty of the programs based on fitness evaluations every 10 workouts. It takes into account, in a loose way, what sort of equipment you have. (Do you have a heart monitor? Do you have hand weights? A Pilates ball? A Step? ) Most importantly it gives you a lot of VARIETY in the exercises you do.
The variety is key, and is more interesting to me than running, as another poster suggested. I know that my wife really likes the program, and she's lost quite a bit of weight with it.
Check out the webpage for the program, easily found through google, and read up on it. Also, read the forums to learn what people do and do not like about it.
Of course, your mileage may vary. I've been using it to try to /gain/ weight and to improve my appetite, as I eat like a bird. Heh. I'm not a pencil neck geek or anything, but I miss the eighteen pounds I lost between 18 and now (29).