Problems with Java in Firefox on Linux

Always get the prompt to download Java for Firefox? Does the manual install also fail to work? Just the FAQs please:

http://plugindoc.mozdev.org/faqs/java.html
http://java.com/en/download/linux_manual.jsp

Firefox 2.0.0.2
JRE 1.5
Linux 2.6.9-42.0.2.ELsmp
CentOS 4