var PrettyAd=new Array()

PrettyAd[0]='<a href="http://www.sherlab.com/katayama/index.htm" TARGET="_blank"><img src="ads/120_katayama_01.jpg" width="120" height="120" border=0 alt="PrettyBikes&trade; by Enrico Katayama"></a>'
PrettyAd[1]='<a href="http://www.sherlab.com/katayama/index.htm" TARGET="_blank"><img src="ads/120_katayama_02.jpg" width="120" height="120" border=0 alt="PrettyBikes&trade; by Enrico Katayama"></a>'

var Pretty=new Array()
var the_one
var z=0
while (z<PrettyAd.length){
the_one=Math.floor(Math.random()*PrettyAd.length)
if (PrettyAd[the_one]!="_selected!"){
Pretty[z]=PrettyAd[the_one]
PrettyAd[the_one]="_selected!"
z++
}
}
document.write(Pretty[1]);