Luego queda así o me equivoco .
 
disculpa que use tus imágenes . 
Ahora veo el parpadeo en el IE y uno leve el Fire Fox . ¿que cosas no? 
Gracias 
Código:
 <html>
	<head>
		<title>
			efecto
		</title>
		<script type="text/javascript">
			var tam1 = 100;
			var tam2 = 0;
			function transitar() {
				if (tam1 > 0)	{
					tam1--; tam2++;
					document.images.img1.style.width = tam1 + "%";
					document.images.img1.style.left = (100 - tam1) + "%";
					document.images.img2.style.width = tam2 + "%";
					document.images.img2.style.left = (100 - tam2) + "%";
					setTimeout("transitar()", 10);
				}
				else	{
					tmp = document.images.img2.src;
					tam1 = 100; tam2 = 0;
					document.images.img2.src = document.images.img1.src;
					document.images.img1.style.width = tam1 + "%";
					document.images.img1.style.left = "0%";
					document.images.img2.style.width = tam2 + "%";
					
					document.images.img1.src = tmp;
					setTimeout("transitar()", 1000);
				}
			}
		</script>
	</head>
	<body onload="transitar()">
		<div id="efecto" style="width: 133px; height: 100px; position:relative">
			<img src="http://www.pepemolina.com/galeria/fotos/mini/Diapositiva81.jpg"
			style="width: 100%; height: 100%; position: absolute; top: 0; left: 0%"
			name="img1" />
			<img src="http://www.pepemolina.com/galeria/fotos/mini/Diapositiva82.jpg"
			style="width: 0%; height: 100%; position: absolute; top: 0; left: 0%" 					name="img2" />
		</div>
	</body>