function validateEnquiryForm(event) {

  var yDom = YAHOO.util.Dom;
  var valid = true;

  if(trim(yDom.get('first_name').value).length == 0) {
    yDom.get('warn_first_name').innerHTML = "Please enter your first name";
    valid = false;
  } else {
    yDom.get('warn_first_name').innerHTML = " ";
  }


  if(trim(yDom.get('last_name').value).length == 0) {
    yDom.get('warn_last_name').innerHTML = "Please enter your last name";
    valid = false;
  } else {
    yDom.get('warn_last_name').innerHTML = " ";
  }
  if(trim(yDom.get('phone').value).length == 0 &&
    trim(yDom.get('email').value).length == 0) {
    yDom.get('warn_phone').innerHTML = "Please enter a phone number or email address";
    valid = false;
  } else {
    yDom.get('warn_phone').innerHTML = " ";
  }

  if(!valid) {
    YAHOO.util.Event.preventDefault(event);
  }
}

function trim(stringToTrim) {
	return stringToTrim.replace(/^\s+|\s+$/g,"");
}
YAHOO.util.Event.onDOMReady(
  function () {
    YAHOO.util.Event.addListener('leadForm', 'submit', validateEnquiryForm);
  }
);