There are lots of free  IDE out there. You could use something lite
like JEdit or TextPad. There are even ones that are free with lots of
wizards for gui development, webservices, etc... like sun one studio
(community edition) or even netbeans. I'm sure there are plenty
others but these are pretty popular and free.

JEdit: http://www.jedit.org/
Sun One Studio: wwws.sun.com/software/sundev/jde/buy/index.html
NetBeans: http://www.netbeans.org/
TextPad: http://www.textpad.com/download/index.html