I have used both Eclipse and NetBeans before, and both were fine IDEs. Right now I'm using Borland's
JBuilder for a CS class, and it also is well done. JBuilder Foundation is the free version, which you can get from here:
http://www.borland.com/downloads/dow...jbuilder.html.
IDEs are fine for learning a language, but there's also something to be said for thoroughly learning and using a multipurpose programming editor, like Emacs or vim. With editors you have a consistency across languages you don't get with language-specific IDEs. There are even IDE-like features available (as extra add-ons) that you might not expect, like language auto-completion or compilation and error-checking tools.