I recommend the A+ for dummies books. I also had a high school class to prepare for the test. The hardware section of the test is the hardest in my opinion (such as the size and purpose of each section of memory, and IRQ assignments). we had trainers in the class that the teacher could program in an error and we would have to figure out what was wrong and correct it.
You also might considering studing for the MCSA/MSCE exam, the Microsoft press training books seem to be good for this.
http://labmice.techtarget.com/MCSE/default.htm