Well, this is not a whole lot to go on, but what the heck. You weigh 260lbs, but how tall are? You want to lose weight? Cardio in the A.M. first thing before you eat. This is the best way to lose weight, no need for phentermine. JMHO. I dont believe in amphetamines as a tool to lose weight. Try lipoflame from Omega, it has nothing but excellent reviews from everyone who uses it. As far as your knees go, there are alot of differant ways to get cardio without stressing your knees. I also have issues with my knees, and I have an elliptical machine that I get great cardio workouts with and its very ergonomic on the whole body. Also, bicycle machine or just a bicycle.
As to your cycle experience, 10 years ago of sust250 for a couple years is kinda vague. Did you run it 2 years straght, or did you cycle on and off for 2 years with pct involved?? I think you should do alot of research and haunt this forum, ask questions that are specific to your goals and desires. And post up more stats and experience. Like BF%, height, WO experience, more regarding how you eat, etc. Let us get to know you better so we have a better idea as to how to help you with what your after.
Welcome to the board by the way.