Don't believe all the negativity
I just took and passed the NASM exam this morning. I have a bachelors and a masters degree but neither are in exercise science, human performance, etc. Due to severe time constraints, I studied the textbook, DVDs and workbook and passed in 3 and a half weeks. It really is not at all as difficult as people on this site and others have said it to be.
I think the practice test adequately prepared me for the final test and I recognized approximately 10-12 questions on the real thing.
Don't spend time on insertion points for muscles, but definitely know what functions the muscles perform and in what plane.
Also my test focused heavily on assessment and which exercises would be suggested for a client in a particular phase of the OPT model as well as what muscles are over or under active when performing overhead squat assessments, etc.
Know what exercises belong in which group (i.e. stabilization, maximal strength, power, etc.)
Given I am a recent masters graduate and still have test taking abilities in me, I still will say to you all that there is no need to get overly worked up about this test. If you read the book, do the exercises, watch the DVDs and master the practice tests, it should be smooth sailing. If I can handle the material in under a month, 2 months should be more than enough time to get the certification in your hands.