Passing PMP is a tough task. it is tough because this requires a consistent effort for around 120 hrs. You can do this 2 hrs for 60 days or 4 hrs for 30 days. However in my experience , passing PMP depends upon the number of practice exams you take and the good news is that these are freely available. Around 70%  of the questions follow the methodology in these sample questions. Targetting around 80% in these sample exams guarantees the success.These are the sites where these sample tests are available.

1. http://www.headfirstlabs.com/PMP/free_exam/  - The questions are having the difficulty low. However lot of questions can be expected with the same levelof difficulty in PMP exams. Target for 90% in these exams.

2. http://techfaq360.com/pmp_5thedition_in.jsp  - Contains very good questions. Directly maps to PMBOK. Very good for stimulating.Difficulty level is low . Target for 85% in this test.

3. http://www.examcentral.net/pmp/pmp-exam-questions - The questions are having the difficulty low. However lot of questions can be expected with the same levelof difficulty in PMP exams. Target for 90% in these exams.

4.http://free.pm-exam-simulator.com/. The  PM Exam Simulator gives you the opportunity to practice taking the PMP Exam in a way that mimics the actual exam.. This is very good. Target for 25 questions out of 30 for the 4 Exams.This exams allows you to study and understand the PMBOK better.

5. http://www.passionatepm.com/free-pmp-exam-practice-test-questions.Very good in praticing exams. The difficulty level is moderate.

6. http://www.brainbok.com/ - Moderately tough questions which checks your understanding.Most importantly refer back to PMBOK for wrong questions.

7. http://www.simplilearn.com/project-management/pmp-certification-training - Very Good Sample Test similar to the toughness in real PMPexam . 75%  is almost a guarantee.

8. www.edwelprograms.com/Free-PMP-Practice-Exam.aspx‎ - Very Good. Getting around 80% is a guarantee.

9. http://www.pmstudy.com/ - Very Good. Getting around  75% is a guarantee.

10. http://206-free-pmp-exam-questions.blogspot.in/p/questions-1-20.html - Very Good questions.Practice this.

The questions in pmzilla are very good. Take the tough questions here.

You can refer to http://www.iwebcircles.com/list/techwizards/p-notes-project-management-p...

Best Wishes,