First, tomcat sucks (in terms of performance) from what I have read. I also read a few posts (elsewhere) that alot of people are disgusted with the bloat and sad performance and other issues with tomcat. Jetty is indeed a lot faster on the servlets, but Jetty does not yet support Servlet 2.3, JSP 1.2, or clustering. Clustering support will be added soon, as will Servlet 2.3/JSP 1.2. Currently Jetty uses the Jasper JSP engine which is really bad. We plan to write a new engine for much faster JSP performance. There is nice Jboss/Jetty integration going on as well.
I have heard good things about the IBM VM, so I would try load testing your site on it on a production quality machine. See if it holds up. If it does, what are you waiting for? IBM is IBM for God's sake! You can't go wrong with them... well, you can if you use Websphere! ;)
Jetty by the way is a full fledged html/servlet/jsp engine. I would toss Apache out and use Jetty for everything. Saves the hassle of trying to figure out Apache for html/shtml, Jetty for servlet/jsp/web container. Up to you, but I prefer the web/servlet container in one as it gives better performance as well.
IBM-JDK: you *CAN* go wrong with them!
A simple test: Try using IBM's JDK with a GUI-intensive program like Together/J -- it's fast, but it's even faster crashing!