Buenas, te dejo acá el código q armé
Código HTML:
<script language="javascript">
function select(form) {
switch(form.Noticiasanteriores.value) {
case "1":
form.action='pagina1.htm';
break;
case "2":
form.action='pagina2.htm';
break;
default:
return false;
break;
}
}
</script>
<form name="form1" method="post" action="" onSubmit='if (select(this) == false) { return(false); } '>
<select name="Noticiasanteriores" id="Noticias anteriores">
<option value="1">Marzo 2005</option>
<option value="2">Abril 2005</option>
<option value="3">Mayo 2005</option>
<option value="4">Junio 2005</option>
<option value="5" selected>Julio / Agosto 2005</option>
</select>
<input name="Submit" type="submit" value="Go">
</form>