You'll need more than just XML::Parser to output the data in X?HTML. XML::Parser, as its name implies, simply parses XML; in fact it's a rather low-level parser, and I think most users of XML use a system that's built upon XML::Parser (XML::Twig, XML::DOM, etc.).

It sounds like what you want is a data-driven site, where the data is stored in XML, and where you can then transform that XML into X?HTML using stylesheets or templates.

I think you should take a look at AxKit (on CPAN: AxKit). It's an "XML Application Server for Apache". And it's very cool. :)