I was told by my trainer that someone who lifts weights for 30 minutes then does 30 minutes of cardio will burn a lot more calories than someone who just runs on the treadmill for 45 minutes. Why, because by the time you get to the cardio you are already at a caloric burn rate.
I also agree with the interval training advice.
I do 2 for 2 minutes. 4 for 2 minutes. 6 for 1 minute. 8 for 30seconds. THEN back down to 2 again. Cardio bursts help a lot!
I personally altered this a bit since I am getting in better shape. You only need to do this 4-5 times.
Good luck! It is a work out that flies by, that's for sure!