I passed a couple of Sun's exams during last two months. Just on Friday passed SCJP 5.0 with 81%. It was fairly tough, lots of tricky questions, especially on threading. One must have really programmed in the language for a while to remember all the tricks in order to pass this test well.
SCEA Part I was not as complicated though (passed it with 89%), studying design patterns and good familiarity with UML should be enough to pass this test. Well, now I have to start working on assignment, that should take a while, probably.
Whizlabs prep software is very good for preparation purposes, although, I think their tests are somewhat more complicated than the ones you get at the real exam.