function openWindow(theURL,winName,winWidth,winHeight,features) {
  var w = (screen.width - winWidth)/2;
  var h = (screen.height - winHeight)/2 - 50;
  features = features+',width='+winWidth+',height='+winHeight+',top='+h+',left='+w;
  window.open(theURL,winName,features);
}

function subscribeNewsletter() {
  openWindow('http://www.tuningdays.at/tinc?key=O3c7K5rX&RegistrationFormID=30566','','350','300','toolbar=no');
}

function unsubscribeNewsletter() {
  openWindow('http://www.tuningdays.at/tinc?key=dcf9U3eK&RegistrationFormID=30566','','350','300','toolbar=no');
}