Today, I finally decided to try Igorsk's scripts on my Kindle so that I can have access to my city's library system if I choose.
I just completed the first step by obtaining my PID and I realized it's exactly the same one generated when I installed MobiPocket 6.0 on my XP laptop. I tried Igorsk's script on my Vista Desktop (one I purchased after I got the PID on the laptop and no file info was cross pollinated). I actually posted about getting the PID from MPR
here.
So some folks may already have their Kindle PID and can skip that step.