$(document).ready(function () {
    $("div#mainmenu li").hover(
            function () {
                $("> .submenu", this).show();
                $(this).prev("li").addClass("previoushover");
            },
            function () {
                $("> .submenu", this).hide();
                $(this).prev("li").removeClass("previoushover");
            }
        );

        // http://www.vancelucas.com/blog/fixing-ie7-z-index-issues-with-jquery/
        if($.browser.msie && parseFloat($.browser.version) < 8)
        {
            $(function () {
                var zIndexNumber = 10000;
                $('div').each(function () {
                    $(this).css('zIndex', zIndexNumber);
                    zIndexNumber -= 10;
                });
            });
        }
});