function popUp(url)
{
    var w = screen.width;
    var h = screen.height;
    var popW = 600, popH = 600; 
    var leftPos = parseInt((w-popW)/2);
    var topPos = parseInt((h-popH)/2);
    var newwin = window.open(url,null,"directories=no,toolbar=no,resizable=no,,width=600,height=600,top=" + topPos + ",left=" + leftPos );
}
function updateInput(itemName,amount)
{
   myform.item_name.value = itemName;
   myform.amount.value = amount;
}
function validateContact()
{
   if (contact.name.value == "" || contact.email_address.value == "" || contact.comments.value == "")
   {
      alert("Please complete the Name, Email Address and Comment fields");
      return false;
   }
   else
      return true;
}