Hey, I just pulled out my front and back ones this week and was able to find cardio kickbox at my local Sports Authority yesterday. So far, I'm really loving them. Quite a good short workout blast. I'm combining them with another workout to maximize my calorie burn.

The Jilliam Michael 30 day shred is great, but I have to loss a little more weight before I can do it all. It hurts me knees..

Have you tried modifying the moves? Level 1 and 2 hurt my knees pretty bad, but level 3 isn't as bad on them. I found that really paying attention to my posture helped out my knees. Good luck!

Some of Jillian's workouts are available at netflix! Try before you buy! I LOVED the Fat blast/Metabolism boost workout. Good combo of kickboxing abd calistenics. Couldn't do it all....I was sweating like I was in a sauna!! Felt real strong afterwards and sore the next day!

Also some of Jillian's videos are on youtube if you want to check them out.
I really like them. I would generally not think I'd approve of such high impact, jerky exercises since I have some occasional lower back issues and old shoulder injury, but I've found that my core is really strong now and my whole body feels REALLY fit. I've been doing them 4x a week for a month and I'm not thinner, but that has more to do with diet I think. Her videos are REALLY hard at the beginning. YOu might not make it through unless you're in great shape already. Go slow, and you will get strong!