I have not tried Slim in 6.. but I bought Power90 this time last year.. and it does work. They are easy to follow exercise tapes and you are encouraged to slow down if the tempo is too fast and you can take breaks if you need to.
I had success with Power90, of course, I quit doing it after a while, but it wasn't the programs fault it was mine.. oh, and they have a wonderful support program filled with message boards and chat.. the site is
www.beachbody.com