var total = 2; 	
var aleatorio = Math.random();
var valor = 1/total;
var achou = false;
var indice = 0;
for (var i=0; i<total && !achou; i++) {
        if (aleatorio>i*valor && aleatorio<=(i+1)*valor) {
                indice = i;
                achou = true;
        }
}
if(i == 1) {
document.write('<a href="programacao.aspx#segunda-feira"><img src="images/ladies.gif" width="255" height="78" alt="" border="0"></a>')
}
if(i == 2){
document.write('<a href="programacao.aspx#sabado"><img src="images/sabado.gif" width="255" height="78" alt="" border="0"></a>')
}