var imagesarr = new Array( 
"1000x163_Eureka_4.swf",
"1000x163_Lafuma.swf",
"1000x163_SCHWINN2.swf",
"1000x163_imidj.swf"); 

var los = Math.floor(Math.random() * imagesarr.length) 
document.write ("<embed src='/flash/"+imagesarr[los]+"' quality='high' pluginspage='http://www.macromedia.com/go/getflashplayer' type='application/x-shockwave-flash' wmode='transparent' width='1000' height='163'>");