I would practice with a book or two, use a CD with a lot of questions, and leave it at that!
I just passed boards this past July. In addition to the above, I took a week long review course (because the hospital paid me to attend), which I would not recommend! It was a waste of time, but maybe it was just that particular course.
I'm glad that I didn't kill myself studying, because it's not something that you can really study for. There were very few straightforward questions (like anat/phys, skills, or disease process) The majority of the questions dealt with prioritizing, delegating, critical thinking. Best advice that I can give you is to remember your ABCs, and steps of the nursing process (ADPIE).
With most of the questions, you could easily eliminate two of the 4 possible answers, and were left with TWO really good answers that were sometimes almost impossible to choose between. Everyone from my class that I've talked to has agreed that their test was also like this. Mine went for 75 questions, as did many of the others that I've talked to.
It was hard, but not any harder than I expected- comparable to nursing school
exams. Relax, you will do fine! The wait after the test to hear if you passed is MUCH worse that the test itself!