function enviar()
{
    if ((window.event ? event.keyCode : event.which) == 13)
    {
  		document.form1.submit();
    }

}
function enviar2()
{
    if ((window.event ? event.keyCode : event.which) == 13)
    {
  		if(document.form2.busca.value != '')
		{
		    document.form2.submit();
			return true;
		}
		else
		{
		     alert('Digite o produto');
			 return false;
		}
		
    }

}