Hi Lynda,
Pilates focuses on core (torso) strength, muscle balance & overall flexibility, but can also include resistance work for the legs & arms. The emphasis is on quality not quantity. It's generally non-cardio (though there are some Pilates inspired cardio videos) so you won't burn a lot of calories.
The leg work varies widely, but generally there's some isolation work that really hits the hamstrings, adductors & abductors. The premise is that most people's quads are much stronger than the other leg muscles. I have strong legs but I feel the burn when doing pilates leg work because it's so focused. Unlike gym style weight work, my legs are still strong for serious cardio work.
I can also tell you that I'm glad that I've done a lot of Cathe strength workouts when we're doing planks & pushups in Pilates! Most of the class are on their knees or in child's pose by the time the instructor is done with us & I can hang with her.
There are LOTS of video choices & you'll just have to find a personality that you like. I like Stott but many find her too dry. Ana Caban is popular, but I don't think her workout flows. There's a lot of pilates inspired workouts too that stray quite a ways from Joseph Pilates work. Do a search here for past recommendations. Also check at Video Fitness for ideas, there are a lot more Pilates people over there.
Debra
Specifically,