I've seen this library before but personally, I prefer doing all AJAX stuff myself. Some time ago I was using AJAX in the admin panel of the system I had designed. In the user management pane you could browse/add/edit/delete users all via AJAX, without reloading the page. Browsing users was the most tricky cause the script downloaded a list of users (id, name, email, level etc) and had to dinamically build the HTML table with that information, I don't know if you can do this kind of thing using a library like XAJAX.
jQuery (or Prototype/mooTools) with JSON :) the way to go.
Just create a little web interface for your AJAX script.
Back from sysadmins to the programmers.