function submitLogin(form){
  if (form.username.value == "" || form._pass.value == ""){
    alert("Preencha os campos E-mail e Senha.");
  }else{
    form._user.value = form.username.value+'@wiig.com.br';
    form.submit();
  }
}

function submitEnter(form,e){
  var key;
  if(window.event){
    key = window.event.keyCode;     //IE
  }else{
    key = e.which;     //firefox
  }

  if(key == 13){
    return submitLogin(form);
  }
}