Thanks. Unfortunately, I wasn't able to solve my problem. I installed J2SE 1.3 and J2EE 1.3, but I had a problem with a connection to my server (localhost).
I searched the web for more information, but I only could find solutions not supported by Sun.
I decided to follow the steps in this
article, and installed J2SE 1.4 and J2EE 1.3. And, for some reason it worked. I had no connection problem with my localhost.