Prepare the same way you did for SCJP. Head First Servlets and JSP is the recommended book around. This week, there's Marcus Green's book promotion. Ask the author some questions, and you may be one of the lucky winners.
I advice that before starting in this exam,make sure you understand all the concepts of the Web and HTTP. This exam is mostly about the Servlet and JSP APIs and don't concentrate on the concepts of the HTTP and Web.
I strongly recommend to read the wonderful book "HTTP The Definitive Guide" by O'reilly.
If you have experiance in developing Web Applications, then go for "Head First Servlets and JSPs" for Bert Bates and Kathy Sierra
Good Luck [ February 23, 2007: Message edited by: Khaled Mahmoud ]
As most of he replies have pointed out, read HFSJ. It's a really good book especially for beginners. You may find that this is not the book for you if you are experienced on servlets and JSPs though, like when you want a quick answer if you forgot something. For that purpose, you have the Servlets and the JSP Specs.