This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Have you tried checking the ports yet? Tomcat runs on port 8080 by default, but that can be overridden in server.xml. It's frequently changed to port 80, which other servers like the Apache Web Server also wants to use.
Port contention is one of the most probable causes of Tomcat start-up failures so it's one of the first things to check.