Egad.
WP Gurus is correct in that if the XML file is "a WordPRess XML" it will import. It will not include your background "stuff", though (the content of your wp-content folder ... images, plug-ins, etc.) Also: anything that's a theme-specific setting (setting for widgets, for example), MAY be there, but if it is you're unlikely to be able to retrieve it.
So the site ITSELF is intact in the XML. The "actual site", though ... is not.