Q482 Is there any way to detect plugins?

<script language="JavaScript"><!--
var can_play = false;

var mimetype = 'audio/midi';

if (navigator.mimeTypes) {
    if (navigator.mimeTypes[mimetype] != null) {
        if (navigator.mimeTypes[mimetype].enabledPlugin != null) {
            can_play = true;
            document.write('<embed src="sound.mid" hidden=true loop=false autostart=false>');
        }
    }
}

function playSound() {
    if (document.embeds && can_play) {
        if (navigator.appName == 'Netscape')
            document.embeds[0].play();
        else
            document.embeds[0].run();
    }
}

function stopSound() {
    if (document.embeds && can_play)
        document.embeds[0].stop();
}
//--></script>

<a href="#" onMouseover="playSound()" onMouseOut="stopSound()"><img src="image.gif" width="100" height="100" border="0"></a>