What has your doctor told you about your knee?
I am familiar with the Leslie Sansone videos and I think they are awesome. I still have a vcr and I also have a DVD of Leslie Sansone's walking program. So, what I'm thinking is - you're doing a lot of high-impact stuff. When you're light-lifting, you're probably also stressing that knee. Does your doctor have any suggestions? Maybe you have chosen the LEAST harmful activities for your knee but are they actually going to help your knee or put more stress on it?
I have arthritis in one part of one foot and I know how bad that can feel. It changes the way I put on shoes. It changes the way I walk. I'm really nervous about doing anything to aggravate that condition but it's my FOOT so there you are...
Do you belong to a gym or Y? For more cardio that probably wouldn't hurt your knee, really long swim sessions or even swim lessons to become more competitive with your swimming can really get your heart rate up.
If I'm totally wrong about the impact on your knee and your doctor actually recommended those activities, well, then - spinning might be for you. It's an activity that I have seen 'shrink' people down several clothing sizes and I've tried it - it's not fun. It's kind of grueling, but you might like the weight-loss rewards. That is, if it doesn't hurt your knee more.