function swapon( imgObj, xid )
    {
        if (imgObj != null)
        {
            imgObj.src  =   images_on[xid].src;
        }
    }

    function swapoff( imgObj, xid )
    {
        if (imgObj != null)
        {
            imgObj.src  =   images_off[xid].src;
        }
    }


    var images_off  =   new Array;
    var images_on   =   new Array;

    function preload_images()
    {
        var i=0;

        for (i=1; i<9; i++)
        {
            images_off[i]       =   new Image;
            images_off[i].src   =   'images/logo' + i + '.jpg';
            images_on[i]        =   new Image;
            images_on[i].src    =   'images/over_logo' + i + '.jpg';

        }

            images_on[9]     =   new Image;
            images_off[9]    =   new Image;
            images_on[10]    =   new Image; 
            images_off[10]   =   new Image;
            images_on[12]    =   new Image;
            images_off[12]   =   new Image;
            images_on[11]    =   new Image;
            images_off[11]   =   new Image;
    
            images_on[9].src     =   'images/over_about.gif';
            images_off[9].src    =   'images/about.gif';
            images_on[10].src     =   'images/over_catalogue.gif';
            images_off[10].src    =   'images/catalogue.gif';
            images_on[12].src     =   'images/over_contact.gif';
            images_off[12].src    =   'images/contact.gif';
            images_on[11].src     =   'images/over_sales.gif';
            images_off[11].src    =   'images/sales.gif';
    }