Don't buy a treadmill, you might as well be doing nothing. Stationary bikes provide much better cardiovascular exercise, and is good for the legs and bum as well! Try pedalling fast for 48 seconds and then sprinting for the last 12 seconds - this is much harder than it sounds and really helps to lose weight and grow fitter. Once you can do this for 15 or 20 minutes after each other, start sprinting for 20 seconds of each minute. Any kind of stationary bike will work, but make sure it has a comfortable seat, otherwise you won't be able to pedal for as long!
I wouldn't advise pills and things like that, they are often dangerous and can seriously screw up your metabolism for life. Good luck with your exercise!
