Hi Nikki! I ordered all 5 just because I had to have them! Love everything that Cathe puts out. I've been doing really well with the PS Series (even added on a few more exercises). You did the right thing by waiting until your comfortable with the PS Series before buying the new Slow & Heavy series. You might also want to consider Leaner Legs. This is a nice variation (well, maybe not nice) from doing PS legs. Just can't wait for those new tapes! Kathy