Ich hab bei mir u. a. so was eingebaut:
<script type="text/javascript">
// Image preloader //
var pic1=new Image(); pic1.src="images/pic1.png";
var pic2=new Image(); pic2.src="images/pic2.png";
var pic3=new Image(); pic3.src="images/pic3.png";
var pic4=new Image(); pic4.src="images/pic4.png";
var pic5=new Image(); pic5.src="images/pic5.png";
var pic6=new Image(); pic6.src="images/pic6.png";
var pic7=new Image(); pic7.src="images/pic7.png";
var pic8=new Image(); pic8.src="images/pic8.png";
var pic9=new Image(); pic9.src="images/pic9.png";
var zahl = 1;
function bildwechsel ()
{zahl++
document.images.hallo.src = "images/pic"+zahl+".png";
if (zahl == 9) {zahl = 0;}}
</script>
<!------------------------------------------>
<img name="hallo" src="images/pic1.png" alt="" onclick="bildwechsel()">
Vielleicht hilft dir das irgendwie weiter ?!
Gruß Wastl