First of all, why do you take the SCJP 5 instead of 6 ?
You don't need to be a genius to pass the SCJP, it's not as hard as you think.
The reason why a lot of people fail is because they underestimate it.
People can code in
Java for 5 years and still not be able to pass the
test. Still they think - since they code for 5 years, how can they not be ready for it - they don't need any form of preparation and fail greatly.
The thing to notice is that there are many little things to watch out for that are impossible to know without studying for it. Some things are just so rarely used that even experienced programmers won't have used it in their career. This does not make the SCJP any harder, you just have to study what is on the exam and you are good to go.
As a study guide I would recommend the Kathy Sierra exam guide. It provides lot's of mock questions throughout the book and another 3 full mock exams on CD.