function Preenche(campo){
	if(document.Form.Nome.value == "" && campo == "Nome" ){
        document.Form.Nome.value = "NOME:";
	}
	
	if(document.Form.Email.value == "" && campo == "Email"){
		document.Form.Email.value = "E-MAIL:";
	}
 }
 
 function valida(){
	
	 if(document.getElementById('nome').value == "" || document.getElementById('nome').value == "NOME:" ){
		 document.getElementById('nome').focus();
		 alert ("Preencha o campo nome.");
		 return false;	
	  }
	  if(document.getElementById('email').value == "" || document.getElementById('email').value == "E-MAIL:"){
		 document.getElementById('email').focus();
		 alert ("Preencha o campo E-mail.");
		 return false;	
	   }
	   
	    if(document.getElementById('email').value!= "")
       {
            var obj = eval("document.getElementById('email')");
            var txt = obj.value;
            if ((txt.length != 0) && ((txt.indexOf("@") < 1) || (txt.indexOf('.') < 7)))
            {
               alert('O campo "Email" está incorreto.');
               document.getElementById('email').focus();
			   return false;
	         }
        }
 }