I learned to use this library in half an hour. Documentation is lacking, or I couldn't find it. But the interface is the same as for IE XmlHttpRequest, so if you look on the internet or in a book for that object, you will get a jump start. I tested it in IE 7. Opera 9.xx and Firefox 2. No complaints whatsoever. I did not really get the PHP backend, but whatever you echo after creating the backend object will end up in your response, so that is easy (if maybe not the proper way!). Good work.