I am a firm believer that weights are a must! Last year I lost a total of 30 pounds with weight training and cardio combined.
Weight training will give you more muscle mass which will allow you to burn more fat when doing cardio, and people with more muscle burn more calories and fat just doing everyday activities.
For years I just did cardio because I hated weight training and that was just for boys- my fitness guru husband told me over and over again that weight training was the way but I wouldn't listen

Eventually I decided to try it and I haven't gone back! Now I do a cardio warm up then some weight training and if I have any energy left over I do a cool down on the treadmill.
I really need to learn to love ab workouts the way I love leg, arm and butt workouts though lol