Here is a great article, written by Ryan Rogers, about how to include resources with your asp.net 2.0 web parts.
http://blogs.msdn.com/ryanrogers/archive/2006/05/01/588166.aspx
He has included really good detail about how to use all the new resource features in .net 2.0. Covers including images and javascript, linking to the included resources, and replacing links to resources in the included files. Great read!