This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
I think Tomcat moved to JSE5 from Tomcat version 5.5 but you could install a compatability patch to allow it to use JSE 1.4.
Since the problem is with Struts I think you're just going to have to run Tomcat using JSE5 (or 6) but should still be able to compile against JSE 1.4