Javascript Example
Screen shot
Javascript code to change image onmouseover and onmouseout.
<html>
<head>
<script type=\"text/javascript\">

function image1()
{
document.getElementById(\"img\").src =\"button_effect2.jpg\";
}
function image2()
{
document.getElementById(\"img\").src =\"button_effect1.jpg\";
}

</script>
</head>
<body>
<a href=\"#\">
<img id=\"img\" border=\"0\" src=\"button_effect1.jpg\" onMouseOver=\"image1()\" onMouseOut=\"image2()\" />
</a>
</body>
</html>

You can download source code here