I passed the Exam P on Oct. 1, 2010. The most important mannual is ASM study guide, and Guo's study guide is good to start. Sample tests are essential for this exam. These three are the main materials I used for Exam P. I  did almost all the practices in ASM and finished all the sample questions. The real exam looks easy to me, probably, 2 to 3 out of 30 maybe wrong by mistake.