Which would be better..

Which would be better riding my stationary bike that has the handle sthat move on it for as long as I can and putting in a few miles, or doing this workout DVD of Jillian Micheals thats 3-2-1- of Cardio...strength..and abs? Which would cause better weight loss?

You will loose weight just doing cardio...and muscle as well. You always need cardio and strenght training combined to look good while losing weight.

As long as you are getting up to your target heartrate and staying there for 15-20mins continuously, I don't really think either one is "better" than the other.

I think I may try alternating them then.. Do one a night and the other the next. I want to find something for strength that is easier on my knee.

Quoting Nightmare in Wonderland:“ I think I may try alternating them then.. Do one a night and the other the next. I want to find something for strength that is easier on my knee.”

That's a good idea. I normally alternate between a "routine" and 3 videos every day. That way I don't get bored with them.

do both. Its better to do a variety of things.