ACDT certification

I am planning on doing the ACDT certification and just wanted to know if anyone here has done it and can give me any advice or suggestions on how I can prepare to take the exam. I am planning on studing on my own, since I really don;t have that much money to take the classes. I have some question and answer material that I got online, plus I am reading Mac OS X Help Desk Essentials by Owen Linzmayer would that be enought to help pass this exam thanks