$(document).ready(function() {
    var currentpage = $("#ctl00_hidCurrentPage").val();

    if (currentpage != "0") {
        $("#nav" + currentpage + "  img").attr("src", $("#nav" + currentpage + "  img").attr("src").replace(".gif", "_on.gif"));
    }

    $("#nav_top  img").mouseover(function() {
        if ($(this).parent().parent().attr("id") == ("nav" + currentpage)) {
            return;
        }
        this.src = this.src.replace(".gif", "_on.gif");
    }).mouseout(function() {
        if ($(this).parent().parent().attr("id") == ("nav" + currentpage)) {
            return;
        }
        this.src = this.src.replace("_on.gif", ".gif");
    });
})