Update DIV when typing in input field

I have an input field, and when I type in it, I want a div to be updated at the same time.

I have a script that works this way, but I've just copied it, and it uses very much code. So I want a very simple one to work. Here's what I've got so far:

JavaScript:

Code:

---

function goCheck() {

        var u_name = document.getElementById('username').value;

        if (u_name!="") {
       
                document.getElementById('output').innerHTML = "<h3>Please Wait, getting results....</h3>";

                var url = 'test1.php';
                var pars = 'output=normal&username='+u_name+'';
               
                var myAjax = new Ajax.Updater( 'output', url, { method: 'get', parameters: pars, onlyLatestOfClass:"htmlfetcher" });

        }

}

---

HTML:

Code:

---

<input type="text" id="username" size="25" onkeyup="goCheck();">                                               

<span id="output"><h3><font color="#D55121" face="arial">The usename will be here</font></h3></span>

---

What should I do to make this work?

Thanks in advance

Take a look at this. It explains it much simpler.

Where are the class "Ajax.Updater"??