Randome page change on refresh

hi there, i having some banners on my website , each time i visit the site, the banner changes randomly, i am using this script

<script language="JavaScript">
<!-- Hide from old browsers

var imagenumber = 3 ;
var randomnumber = Math.random() ;
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;
images = new Array
images[1] = "1.swf"
images[2] = "2.swf"
images[3] = "3.swf"
var image = images[rand1]
// -- End Hiding Here -->
</script> <script language="JavaScript">
<!-- Hide this script from old browsers --
//document.write('<embed SRC="images/' + image + '" width="753" height="410">')
document.write('<embed src="' + image + '" quality="high" pluginspage="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash" type="application/x-shockwave-flash" width="753" height="410"></embed>')
// -- End Hiding Here -->

And it is working properly.
But the problem i am facing is i want to add a prameter with value…
for eg. <param=movie value=wsmode>

please help me… how can i add a flash param. in this javascript. and where to put the param.?