Power Hour is similar in format to MIS, but concentrates more on muscular endurance, giving little rest time in between each exercise. The weights you use for this will be a bit lighter than in MIS due to that format. I believe it sarts out doing squats (grueling), than goes to chest, then lunges (more horrific muscle failure), then back, shoulders, biceps, triceps, and finally abs.
Some of Cathe's earlier step tapes may be appropriate for you to try, but don't jump in too quickly. There's no point in getting frustrated when you can build up to her stuff in a less frustrating way. I'm' not sure what step tapes you already have, but if you haven't tried Gin Miller, I would suggest Reebok's Circuit Challenge and Aerostep as good transitions tapes. Also, Kathy Smith step tapes. These can be purchased very cheaply (check amazon.com and other sites), so if they end up being too basic you haven't lost much. Or, if you already know the terms basic, turn step, hop turn, repeater, across the top, etc. you could possibly try Cathe's Wedding Video. I am not a big fan of this tape because there is too much whooping, but the choreograpy will lead you into Cathe's other more advanced stuff very well. If you have a DVD player, Cathe's Cardio Classics DVD may also be a good place to start.
I hope this helped a little.
Wendy