Es un formulario mas o menos asi, almenos eso intente hacer para que funcionara:
Código HTML:
<form name="doublecombo" action="buscar.php" method="post" target="_blank">
<center>
<INPUT type="text" name="palabra" size=60" value="" ><br>
<input type="radio" name="pais" value=0 >Universidades
<input type="radio" name="pais" value=1 >Intitutos
<input type="radio" name="pais" value=2 >CFT
<select name="stage2" size="1">
<option value="uc">U de Concepcion</option>
<option value="us">U de Santiago</option>
<option value="uct">U catolica</option>
</select>
<input type="button" " value="Go!">
</p>
<script>
<!--
/*
Double Combo Script Credit
By JavaScript Kit (www.javascriptkit.com)
Over 200+ free JavaScripts here!
var groups=document.doublecombo.pais.options.length
*/
var groups=3
var group=new Array(groups)
for (i=0; i<groups; i++)
group[i]=new Array()
group[0][0]=new Option("udec","uc")
group[0][1]=new Option("ustgo","us")
group[0][2]=new Option("ucat","uct")
group[1][0]=new Option("Duoc","duoc")
group[1][1]=new Option("V.Gomez","gome")
group[2][0]=new Option("Cepech", "cepech")
group[2][1]=new Option("Rodain", "rodain")
group[2][2]=new Option("Manpower", "mpower")
group[2][3]=new Option("Crecic", "crecic")
var temp=document.doublecombo.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
}
//-->
</script>
</form>