anyone know a low impact version of circuit training?

AmyG1024

I recently tried Jillian Michaels 30 day shred. In some ways I like it. Work like heck for 20 minutes and call it good. That said, my knees really don't like bouncing that much anymore (jogging in place, "jumping rope", jumping jacks, etc). So, I'm wondering if anyone in this group knows of a good circuit training type video that is low/lower impact on the aerobics part.

Thanks!
Amy