Show/hide checkbox div on change and load
It could be done with:

$(document).ready(function() {
    $("input").change(function() {
        var index = $(this).closest("li").index();
        $(".metabox").eq(index)[this.checked ? "show" : "hide"]();
    }).change();
});​


http://jsfiddle.net/bK8EC/118/

Remember to add proper qualifiers in your real code, for example add id="something" to your ul and then do $("#something input:checkbox") instead of just binding this event to every input on the page. The .metabox is also pretty fragile if a container isn't added.