First, I want to say good for you to want to improve your health.
Then, after that, I think you should just choose a DVD, and then as you get into it, go get the other. The best way to maintain a healthy exercise program is to have variety. Doing the same routine over and over not only gets your body used to that routine, but also becomes dull. Personally, I enjoy a variety of Leslie Sansone's DVDs and have been doing those for a decade now.
I've known quite a few friends on weight watchers, and combining the program with exercise has really helped them lose weight and maintain the weight loss. Your are on on the right track!
Good luck and enjoy!