The apps we write typically store user information in databases and configuration information in xml files. When I want to view the contents of an xml file, I just click on it and Windows XP uses Internet Explorer to show a read only view of the file. This is not bad and I've kinda gotten used to it. I recently ran across a program that does a better job though. It only allows you to view, not edit, but it's a quick and simple replacement for the IE xml viewer built-in to XP. It also allows you to search based on XPath expressions which is helpful. You can download source or just install the executables at http://www.codeplex.com/xmlexplorer.