>I just don't understand the advantage of using XML over using a database, especially for web apps. Why not just use ADO so you can use SQL, etc., to get, update data from a database? Is XML faster, more flexible? Any explanations with examples would be helpful.

XML is a flexible way to store data that any platform can read, unlike ADO or SQL. By any platform, I mean any os (Windows, Unix, Mac, Linux, ect.) or any device (Cell Phone, PDA, Pager, ect.).