Running is bad on the joints for runners of all shapes and weight. I would lose the weight before starting a running program. Because running is in general bad for the joints, I would suggest biking, roller-blading etc.
EDIT: Ok so after doing more a recent study of the impacts of running, it appears that perhaps running is now considered less harmful on the joints as previously thought. However, don't over-do it, listen to your body, be aware of any pain.
