> Why doesn't this work?
Because IE's support for XML is not yet complete: it's experimental.
> Question 1.
> I try to display a XML document in IE 5.0 (using a CSS), but it only
> works without a DTD. And if I don't use a DTD and try to declare
> character references, then it complains that elements used in the
> document are not declared in the DTD.
Not only is it experimental, it's broken in places.