function centeredPopup(mypage, myname, w, h, scroll) {
   var winl = (screen.width - w) / 2;
   var wint = (screen.height - h) / 2;
   winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',scrollbars='+scroll+',resizable'
   win = window.open(mypage, myname, winprops)
   if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}

$.fn.preload = function() {
    this.each(function(){
        $('<img/>')[0].src = this;
    });
}

$(function() {
    $('img[data-hover]').hover(function() {
        $(this).attr('tmp', $(this).attr('src')).attr('src', $(this).attr('data-hover')).attr('data-hover', $(this).attr('tmp')).removeAttr('tmp');
    }).each(function() {
        $('<img />').attr('src', $(this).attr('data-hover'));
    });;
});