function ValidateForm(form)
{
if(form.area.value=="")
   { 
      alert('You must enter an area to calculate')
      form.area.focus(); 
      return false; 
   }  
 if(form.county.value=="")
   { 
      alert('Please select a County') 
      form.county.focus(); 
      return false; 
   }  
 return true;
 }
 
  function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }