Welcome to the ranch. You may not be used to the ranch yet, but there is a forum dedicated to SCJP. This forum is for Sun Certification Results. You should post your question in the SCJP forum. Maybe a moderator will move your thread for you.
Also, your name does not comply to the Javaranch Naming Policy Could you please check it out, and change your name accordingly ? Thank you for your comprehension. http://www.javaranch.com/name.jsp
Concerning your question, I'd advice you to go for 5.0. There's been many new features which are being used more and more.