Something

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">	
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="fr" lang="fr">
 <head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  <title>Example</title>
 </head>
 <body>
  <!-- HTML -->
  <div><input type="text" id="login" /></div>
  <!-- JS -->
  <script type="text/javascript">
  <!--
  var login = document.getElementById('login');
  if(login.value=='') login.value = 'Login';
  login.onfocus=function(){
    if(this.value=='Login') this.value='';
  }
  //-->
  </script>
 </body>
</html>