Kodlarla biraz oynadım ama istediğin bu sanırım al bakalım.

<html>
<head>
<script type="text/javascript" src="http://jqueryjs.googlecode.com/files/jquery-1.3.2.min.js"></script>
<script type="text/javascript">        	
$(document).ready(function(){

    //Set opacity on each span to 0%
    $(".rollover").css({'opacity':'0'});

	$('.img_hover').hover(
		function() {
			$(this).find('.rollover').stop().fadeTo(500, 1);
		},
		function() {
			$(this).find('.rollover').stop().fadeTo(500, 0);
		}
	)

});		
</script>
<style type="text/css">
* { margin: 0; padding: 0; }
.img_hover { width: 32px; height: 32px; position: relative; display: block; cursor: pointer; }
.img_hover .rollover { width: 32px; height: 32px; display: block; position: absolute; left: 0; top: 0; }
</style>	
</head>
<body>
<p class="img_hover">
	<span class="rollover"><img src="http://cdn.iconfinder.net/data/icons/woothemesiconset/32/error_button.png" alt=""/></span>
	<input name="submit" type="image" src="http://cdn.iconfinder.net/data/icons/woothemesiconset/32/search_button_green.png" id="submit" tabindex="5" class="submit_button" value="Yorumu Gönder" />
</p>
<p>
	<input type="hidden" name="comment_post_ID" value="<?php echo $id; ?>" />
</p>
</body>
</html>