var how_many_ads = 4;
var now = new Date()
var sec = now.getSeconds()
var ad = sec % how_many_ads;
ad +=1;

if (ad==1) {
banner="swfs/empire1";
}

if (ad==2) {
banner="swfs/empire2";
}

if (ad==3) {
banner="swfs/empire3";
}

if (ad==4) {
banner="swfs/empire4";
}

AC_FL_RunContent('codebase','http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0','width','900','height','525','wmode','transparent','src','' + banner + '','quality','high','pluginspage','http://www.macromedia.com/go/getflashplayer','movie','' + banner + '');