Thanks, given me some more scope to work with.
I can put a picture in a separate DIV but then I need to pass a variable from each mouseover event to indicate which picture was involved, rather than four different routines.
Also I can't get any sound anyway. this is what I'm using so far based on one by JavaScript Archive. Works fine until Netscape 6 even if I load the LiveAudio plugin.

<script type="text/javascript"><!--
// Preload and play audio files with event handler (MouseOver sound)

var aySound = new Array();
// Below: source for sound files to be preloaded
aySound[0] = "concorde.wav";
aySound[1] = "concordetakeoff.wav";
aySound[2] = "hovercraft.wav";
aySound[3] = "sonar.wav";
aySound[4] = "rocketcountdown.wav";

// DO NOT edit below this line
document.write('<BGSOUND ID="auIEContainer">')
IE = (navigator.appVersion.indexOf("MSIE")!=-1 && document.all)? 1:0;
NS = (navigator.appName=="Netscape" && navigator.plugins["LiveAudio"])? 1:0;
ver4 = IE||NS? 1:0;
onload=auPreload;

function auPreload() {
if (!ver4) return;
if (NS) auEmb = new Layer(0,window);
else {
Str = "<DIV ID='auEmb' STYLE='position:absolute;'></DIV>";
document.body.insertAdjacentHTML("BeforeEnd",Str);
}
var Str = '';
for (i=0;i<aySound.length;i++)
Str += "<EMBED SRC='"+aySound[i]+"' AUTOSTART='FALSE' HIDDEN='TRUE'>"
if (IE) auEmb.innerHTML = Str;
else {
auEmb.document.open();
auEmb.document.write(Str);
auEmb.document.close();
}
auCon = IE? document.all.auIEContainer:auEmb;
auCon.control = auCtrl;
}
function auCtrl(whSound,play) {
if (IE) this.src = play? aySound[whSound]:'';
else eval("this.document.embeds[whSound]." + (play? "play()":"stop()"))
}
function playSound(whSound) {
document.write(whSound);
if (window.auCon) auCon.control(whSound,true); }
function stopSound(whSound) { if (window.auCon) auCon.control(whSound,false); }
//-->
</script>