I think, for starters, it would probably help if you read the FAQ here and Sun's own description of the exam at their site. Also, search this forum, as there are book recommendations folks have made in the past which are fairly helpful.
The first thing I would honestly say is that the best preparation for an exam like this is experience doing exactly what it is testing. You're going to want to have done software architecture (or at least have a solid grasp on the concepts) before you start the process, since it does get fairly involved.
For Part I, you're going to need to brush up on J2EE 1.2, since that's what the exam is based on (including EJB 1.1). I didn't find this section too terribly difficult.
Part II is a take-home assignment where that pesky OOAD stuff comes in. This section can have any non-beta Java EE release as the technology base, so use which one you feel strongest with. And Part III is an essay exam to simply validate that you did the work in Part II.
HOpe that helps.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!
As far as the exam is concerned (http://www.sun.com/training/certification/java/scea.xml) it does not have any pre-requisite certifications. But I would recommend the following approach. 1. Take a look at the objectives and find out the topics you are already comfortable with. 2. If you are comfortable with most of the objectives you can already try out a mock test to find out where you stand. 3. But if you find that you need to learn with most of the topics then start with core concepts like OOAD, UML, EJB, EJB container model, design patterns, messaging, protocols and internalization. This is a big list but no other go. 4. Now you can start actual architectural concepts which are covered more in rest of the objects. 5. Do some more mock tests and you are ready for the exam.