rimages = new Array();
rimages[rimages.length]='http://www.commtank.com/images/header-images/temp-header-1.jpg';
rimages[rimages.length]='http://www.commtank.com/images/header-images/temp-header-2.jpg';
rnum = Math.floor(Math.random() * rimages.length);
document.write("<img src='"+rimages[rnum]+"'>");