As always, I'll just try to answer the best way I understand so far. What about creating some custom ASP.NET server controls to translate the XML into HTML? You might have a control for tables, one for divs, one for paragraphs, etc. You might even be able to inherit from HTMLGenericControl for each of these and override the rendering to translate into what you want.
Again, I could totally misunderstand your question, but I'm imagining a class that would act as a controller where the XML would be sent. This might call off to a factory that would generate the correct type of custom control to handle the XML and translate it to the desired HTML and CSS?
Could you post an example of the XML content?