I want to develop a web site in XML. What software is required and where can I find it?
xml.apache.org for the Xerces parser and the Xalan XSL-T engine;
jakarta.apache.org for a servlet engine to build on;
Producing useful translations from XML using XSL is half the battle. You should get hold of the Mulberry reference cards, and I found that Neil Bradleys "The XSL Companion" was a decent reference.
Finally you can't mention places to get XML tools without alphaworks - lots of IBM stuff you can download, including an XSL editor.