$.fn.extend({

 	rollOver : function(){

 		$(this).each(function(){
 			var image = new Image();
 			image.src = $(this).attr('alt');
 		});

 		var onMouseOver = function(){
 			$(this).data('tmp', $(this).attr('src'));
			$(this).attr('src', $(this).attr('alt'));
		};
		
		var onMouseOut = function(){
			$(this).attr('src', $(this).data('tmp'));
		};

	 	$(this).hover(onMouseOver, onMouseOut);
	 	
	}

});

$(document).ready(function(){
	$(".msg-links img").rollOver();
});