$(document).ready(function() {
    var div_na = $('#main_menu div.item:not(.active)');

    var div = $('#main_menu div.item');

    div.bind('click',function(){
        window.location = $(this).find('a').attr('href');
    });

    div_na.bind('mouseover',function(){
        $(this).removeClass('active').addClass('active');
    });

    div_na.bind('mouseout',function(){
        $(this).removeClass('active');
    });
});