Try something like this maybe, could be easier to read and see for you anyway
Code:
$content = sprintf('<li id="thumb"><a href="%s"
onMouseOver="showThumbnail(\'%s\',event)"
onMouseOut="closeThumbnail()"
rel="bookmark" title="Permanent Link: %s">%s</a></li>',
get_permalink(),
$thumb,
the_title('','',FALSE),
the_title('','',FALSE)
);