XML is not a generic layout system. XML is a Markup Language describing a grammar that you can use to specify a format for documents. XML is born of SGML.

Currently, the buzzword compliance police state that you should obviously use XML -- but as always it depends on what you need to model.

If the data is simple, XML may be overkill -- but if want to present via web browsers then XML and XSLT may be the way to go.