Originally Posted by chrisd_b
If your after cardio - do light weights.
If your after size - do big weights.
That's not correct. All weight training is pretty much Anaerobic, even at low intensity and high reps. Without getting too technical, Anaerobic exercise will not neccesarily lose you weight or improve lung or heart function.
If you want to get fit, ie improve your lung capacity and heart function then you need to do Aerobic work, ie Running, swimming, cycling.
I agree that the various CV machines are pretty worthless though. rowing is a good comprimise between Aerobic/Anaerobic however.