(Eclipse 3.4, Ganymede)
I have an existing Dynamic Web Application project in Eclipse. When I created the project, I specified \'Default configuration for Apache Tomcat
This may be old but I tried and found the following in eclipse Galilio.
Open the navigator view and find that there is a .settings folder under your project expand it and then open the file: org.eclipse.wst.common.project.facet.core.Delete the content of this file and right click on the project and click on properties. Go to Project Facats in the popup window there you can click on runtime tabs and convert your project to the new facet you want.