The xml element for HTML is entirely non-standard and very very badly supported.
If you want to generate a data table using an XML source then you are better off using some server side technology that outputs regular HTML.
Failing that, consider the YUI Data Table widget, which can use an external XML file as its data source.
http://developer.yahoo.com/yui/datatable/
Note, however, that this approach doesn't have a non-
JS fallback. So you can say goodbye to support from a lot of clients (including Opera Mini and GoogleBot). Server side is better as it only requires the client to support basic HTML.