Add item to beginning / top of dropdown list

[Krokonoster]

How to one ensure the following will add an option to a dropdownlist, but at the top of the list? (since the list will already be populated in my case)

    $.fn.prependSelect = function (value, text, selected) {
        return this.each(function () {
            if (this.tagName == 'SELECT') {
                var dropdownList = this;
                var option = new Option(text, value, selected);
                if ($.browser.msie) {
                    dropdownList.add(option);
                } else {
                    dropdownList.add(option, null);
                }
            }
        });
    };

Thanks in advance!