You might want to maintain XML information on the server and format it as HTML to send to the client. You can do so using any server-side techniques, such as from script in an ASP page. In addition, you can use XSL to format the information. See Using XSL in an Active Server Page.
Note that if the client is Microsoft® Internet Explorer 5 or later, you can send an XML file with an embedded XSL reference, and the browser will automatically format the sent XML using the referenced style sheet. See XML and Style Sheets.
See also Serving Up XML.