Hi Praveen:
I am not sure with 20 days if you can get the full benefit from the PM Prepcast. It won't hurt but it isn't designed for rush studying. I definitely recommend the exam simulator. It is a real good indicator of where you need to focus your studies. It also teaches you time management for the real exam.
I recently read another post (
www.project-management-prepcast.com/kune.../4431-passed-the-pmp
) that you may benefit from their study plan.
Practise writing out your formulas. Don't just memorize your definitions, processes and ITTOs. Understand the context of how they work together and how they flow.
Good luck.
Tracey