On Ubuntu 7.04, I see two packages that should satisfy your requirements. tomcat5 will install Tomcat 5.0, or you could use the tomcat5.5 package to install Tomcat 5.5. There are packages for administrative web interfaces for Tomcat (package name plus -admin).
To install Tomcat 5 plus the admin interface:
sudo aptitude install tomcat5 tomcat5-admin
Or if you want to use Tomcat 5.5 plus the admin interface:
sudo aptitude install tomcat5.5 tomcat5.5-admin
Tomcat will be installed and should be automatically configured. You can connect to the machine with it's IP address and the associate ports that Tomcat and Tomcat web admin run on.
If you're planning on running a desktop environment, I would recommend using another free virtualization product like VMware Player. There are video and mouse issues with Virtual PC out of the box on Ubuntu 7.10. If you're using the server install it shouldn't matter.