My pull-up plan

Been working on the gravitron for several weeks now. For those of you who don't know, this is a machine that allows the user to do pull-ups (wide angle or narrow grip) with assitance. One can also do dips. The cool thing about this machine is one can vary the amount of assist. Last week I was down to 100 pound of assist. I figure that if I step down the assist by one level (10 pounds) each week, theorectically I will be able to do pull-ups unassisted in 10 weeks.
So tonight, I stepped down to 90 pounds of assist. I did three sets of 15 reps of wide grip and 3 sets of 15 reps for narrow grip. Between each set, I did a round of hip exercises on the multi-hip machine since it is right next to the gravitron.
I'm going to be sore tomorrow.....
By my calculations, by the week of April 10 (tax week) I should be able to do a pull up unassisted. We'll see.
Did 45 minutes of cardio tonight. I really detest cardio. It's a love-hate relationship. I hate it, but really love that i do it.