Ayuda con Formulario

[dudu_10]

Hola quisiera saber como puedo modificar este formulario para que al seleccionar la ultima opcion me envie a una ventana nueva

gracias d antemano

<FORM name="isc">
<table border="0" cellspacing="0" cellpadding="0">
<tr align="center">
<td nowrap height="11"> &nbsp;
<select name="example" size="1" onChange="redirect(this.options.selectedIndex)">
<option selected>Seleccionar...</option>
<option>1</option>
<option>2</option>
<option>3</option>
</select>
<select name="stage2" size="1" onChange="redirect1(this.options.selectedIndex)">
<option value=" " selected> </option>
<option value=" " selected>......</option>
<option value=" " selected>......</option>
</select>
<select name="stage3" size="1" onChange="redirect2(this.options.selectedIndex)">
<option value=" " selected> </option>
<option value=" " selected>......</option>
<option value=" " selected>......</option>
</select>
<script>
<!--
/*
Triple Combo Script Credit
By Hamid Cheheltani/ JavaScript Kit (http://www.javascriptkit.com)
Visit http://javascriptkit.com for this and over 400+ other scripts
*/
var groups=document.isc.example.options.length
var group=new Array(groups)
for (i=0; i<groups; i++)
group[i]=new Array()
group[0][0]=new Option("......"," ");
group[1][0]=new Option("Tipo"," ");
group[1][1]=new Option("opcion 2","47");
group[1][2]=new Option("opcion 21","47");
group[2][0]=new Option("Tipo"," ");
group[2][1]=new Option("opcion3","115");
group[3][0]=new Option("Tipo de Carta"," ");
group[3][1]=new Option("opcion4","115");
var temp=document.isc.stage2
function redirect(x){
for (m=temp.options.length-1;m>0;m--)
temp.options[m]=null
for (i=0;i<group[x].length;i++){
temp.options[i]=new Option(group[x][i].text,group[x][i].value)
}
temp.options[0].selected=true
redirect1(0)
}
var secondGroups=document.isc.stage2.options.length
var secondGroup=new Array(groups)
for (i=0; i<groups; i++) {
secondGroup[i]=new Array(group[i].length)
for (j=0; j<group[i].length; j++) {
secondGroup[i][j]=new Array() }}
secondGroup[0][0][0]=new Option("....."," ");
secondGroup[1][0][0]=new Option("....."," ");
secondGroup[1][1][0]=new Option("Tipo"," ");
secondGroup[1][1][1]=new Option("opciones","XXXXXXXXXXXXXXXXXXX");
secondGroup[1][2][0]=new Option("Tipo"," ");
secondGroup[1][2][1]=new Option("opciones","XXXXXXXXXXXXXXXXXXX");
var temp1=document.isc.stage3
function redirect1(y){
for (m=temp1.options.length-1;m>0;m--)
temp1.options[m]=null
for (i=0;i<secondGroup[document.isc.example.options.selectedIndex][y].length;i++){
temp1.options[i]=new Option(secondGroup[document.isc.example.options.selectedIndex][y][i].text,secondGroup[document.isc.example.options.selectedIndex][y] [i].value)
}
temp1.options[0].selected=true
}
function redirect2(z){
window.location=temp1[z].value
}
//-->
</script>
</td>
</tr>
</table>
</FORM>

[dudu_10]

bueno creo q no me pueden ayudar ......