Unfortunately, MOSS does not support saving publishing sites as a template. There are two things you can do to get around this - Deactivate the Publishing feature, create your template and then turn it back on again, or simply append /_Layouts/AreaTemplateSettings.aspx to the end of the base URL to create the template.
Be aware that if you have applied any master pages or style sheets that depend on the publishing features, this may not work too well. If this is a possibility, try it in a dev environment first. Good luck! :-)