hey guys. i have the following code which works. The code automatically updates a div every X seconds. Im new to usig Javascript so really struggling with what im trying to achieve. Basically the code works but the fade fuction is not doing what i want. I only want the fadein to apply to new posts in the div.

eg. if div displays '1, 2" i want "1, 2" to fade in, but when i update the div again i only want NEW data to fade in, rather than the entire div. So if i enter "3" in to the div, "3" fades in, not "1,2,3". Basically im looking for something similar to the bbc ajax script.

Code:
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>

<script language="javascript">
function getRefresh()
{
	$("#auto").fadeIn("slow");
	$("#auto").load("ajax.php", callback);
}

function callback() 
{
	$("#auto").fadeOut("slow");
	setTimeout("getRefresh();", 1000);
}
	$(document).ready(getRefresh);

</script>


</head>

<body>

<div id="auto">
Random text goes here
</div>
</body>

</html>