You don't necessarily have to spit out the entire page in XML, just the data that you want rendered. Use an <object> tag or something to embed the data in your document, or use an ActiveX control or Java applet to do the XML rendering, and have it request the data in XML form on its own.

Anyways, I was just offering that as a possible alternative for anyone else that's looking at doing something similar. It may not be useful in this case but it might be for other potentials.