Pilates is a really great idea, but I would recommend going for a few classes first if you can. Pilates is really effective IF done properly and it can be really helpful to have an instructor look at your technique. If you do it at home by yourself, be careful as you could hurt yourself

Also if you are going to do it at home make sure you get a beginners DVD which will explain everything for you and won't throw in any advanced exercises that you shouldn't be attempting yet.

I hope I didn't sound discouraging - I don't mean to

Also combining the Pilates with some Cardio would be beneficial and good luck