Enlazar 2 listbox en un mismo asp

Hay muchasmaneras de hacerlo, la + conocida es Javascript... ahi va un ejemplo de un script mio llamado busco.asp
<!-- #include file="../asp/inc_Funciones.asp" -->
<%
nombreusu=Request("nombreusu")
'OUT nombreusu &BR
%>
<TITLE>Buscador</TITLE>
<link rel="stylesheet" type="text/css" href="/archivos/estilos/estilos.css">
<script>
// Tablas
function MenuOn(obj,color,msg)
{
obj.bgColor = color;
obj.style.cursor = 'hand';
if (!msg)
msg = '';
window.status = msg;
return true;
}
function MenuOff(obj,color,msg)
{
obj.bgColor = color;
obj.style.cursor = 'default';
window.status = '';
return false;
}
function MenuGo(url)
{
window.location = url;
}
</script>
</HEAD>
<SCRIPT LANGUAGE="JavaScript">
var lavision = false
var popup_zona = null;
function cerramos(){
if (lavision){
lavision=false;
if (!winvision.closed){
winvision.close();
}
}
}
function cargamos(quecarga,quewin,wid,hei){
cerramos()
lavision=true;
winvision=window.open(quecarga,quewin,"status=no,menubar=no,toolbar=no,resizable=yes,scrollbars=yes,width="+wid+",height="+hei+",top=0,left=0");
}
function funciones(){
popup_zona.close();
}
</SCRIPT>
<SCRIPT language="JavaScript" type=text/javascript>
var popup = null;popup2 = null;
function imagen(ancho,alto,file,alt){
if(ancho > window.screen.width){
wi=window.screen.width - 20
}else{
wi=ancho
}
if(alto > window.screen.height - 120){
hei=window.screen.height - 120
}else{
hei=alto
}
if ( ( popup == null ) || popup.closed ){
// open the window again
popup = window.open('includes/popup.cfm?wid=' + ancho + '&hei=' + alto + '&file='+ file + '&alt=' + alt,'popup','width=' +wi + ',height= '+hei+',left=0,top=0,scrollbars=yes,resizable=yes');
window.popup.focus();
}else{
window.popup.close();
popup = window.open('includes/popup.cfm?wid=' + ancho + '&hei=' + alto + '&file='+ file + '&alt=' + alt,'popup','width=' +ancho + ',height= '+alto+',left=0,top=0,scrollbars=yes,resizable=yes');
// bring the window to the front
window.popup.focus();
}
}
</SCRIPT>
<SCRIPT language=javascript>
a = new Array("Argentina,1");
a_1 = new Array("Capital Federal,1" , "Buenos Aires,2" , "Catamarca,3" , "Chaco,4" , "Chubut,5" , "Córdoba,6" , "Corrientes,7" , "Entre Ríos,8" , "Formosa,9" , "Jujuy,10" , "La Pampa,11" , "La Rioja,12" , "Mendoza,13" , "Misiones,14" , "Neuquén,15" , "Río Negro,16" , "Salta,17" , "San Juan,18" , "San Luis,19" , "Santa Cruz,20" , "Santa Fé,21" , "Santiago del Estero,22" , "Tierra del Fuego,23" , "Tucumán,24" );
a_1_1 = new Array("Capital Federal,1" );
a_1_2 = new Array("Gran Bs. As. Norte,1" , "Gran Bs. As. Noroeste,2" , "Gran Bs. As. Oeste,3" , "Gran Bs. As. Oeste Sur,4" , "Gran Bs. As. Sur,5" , "Costa Atlántica,9");
a_1_1_1 = new Array("Almagro,1" , "Barrio Norte,2" , "Belgrano C/Chico/Barrancas,3" , "Belgrano R,4" , "Boca/Barracas,5" , "Boedo,6" , "Caballito,7" , "Centro (Vivienda),8" , "Centro Norte (Comercial),9" , "Cen