NetBeans With J2EE versus Sun One Studio Enterprise
Which of the two would be more appropriate to use for creating GUI applications? Which one would be more appropriate for an EJB based web application?
Sun One Studio is Netbeans with additional "enterprise" functionality. As thing now stand, S1S is 1-2 releases behind NB, due to the time required to add the additional functionality. The added stuff is useful for large systems, and Sun supports S1S - but not NB.
Depending on your specific requirements, either one might do the job.
Both are now free, and it appears that they will stay that way.
And both can use Application Server and Tomcat (or JBoss, etc in the the case of NB 5), and both work with J2EE.