function valida(form) {
	if (form.nome.value == ""){
		alert('Favor preencher o campo Nome.');
		form.nome.focus();
		return false;
	}	
	else if (form.email.value == ""){
		alert('Favor preencher o campo Email.');
		form.email.focus();
		return false;		
	}
	else if (form.email.value.indexOf("@") <= 0 || form.email.value.indexOf(".") <= 0){
		alert("Formato do email inválido.")
		form.email.focus()
		return false;
	}
	else if (form.telefone.value == ""){
		alert('Favor preencher o campo Telefone.');
		form.telefone.focus();
		return false;		
	}
	else if (form.empresa.value == ""){
		alert('Favor preencher o campo Empresa.');
		form.empresa.focus();
		return false;		
	}
}