I started of with 'A Programmer's Guide to
Java (tm) Certification'
by Rolf Rasmussen - it's very complete if you're looking for more info / greater depth. That said I found it a hard read - when I later came across K&B was soooo much clearer. The Exam cram book by Bill Brogden is spot on for revision in the week or two before the exam.
(Now I've passed the exam, it the Rasmussen book that I turn to if I need to look something up).
Good luck,
Louise