var img=new Array(
new Array('images/ad_sw_securities.jpg','http://www.southwestsecuritiesfsb.com'),
new Array('images/ad_durant_toyota.jpg','http://www.duranttoyota.com'),
new Array('images/ad_durant_autoplex.jpg','http://www.durantautoplex.net'),
new Array('images/ad_first_nat.gif','http://www.ffinbank.com'),
new Array('images/ad_decordova_ranch.jpg','http://www.decordovaranch.com/'));

var rn=Math.floor(Math.random()*img.length);

document.write("<a target=_blank href="+img[rn][1]+"><img SRC="+img[rn][0]+"></a>");