I went for the web component exam, passed and I am currently studying for the business component exam.
I am glad that I did because of these reasons:
1. I feel that business component exam has a lot less contents to study for.. if you take the business component exam first, you will be overwhelmed by the web component exam contents.
2. I am using EJB3.1 cookbook as my exam guide and the book uses servlets to
test concepts. Since I know servlets, it's much easier!
3. Many of the things I studied for the web component exams are used in the business component exam(mostly, the annotations and security stuffs)
Good luck, whichever way you decide to go.
