function MC_popup(url) {

var width  = 400;
var height = 300;
var left   = (screen.width  - width)/2;
var top    = (screen.height - height)/2;
var params = 'width='+width+',height='+height;
params += ',top='+top+',left='+left;
params += ',directories=no';
params += ',location=no';
params += ',menubar=no';
params += ',resizable=no';
params += ',scrollbars=no';
params += ',status=no';
params += ',toolbar=no';
newwin=window.open(url,'newsletter_signup', params);

if (window.focus) { newwin.focus(); }
return false;
}