<form>
<input type="radio" onclick="javascript:this.form.action='a.php';this.form.submit()">
<input type="radio" onclick="javascript:this.form.action='b.asp';this.form.submit()"
</form>
<input type="radio" onclick="javascript:this.form.action='a.php';this.form.submit()">
<input type="radio" onclick="javascript:this.form.action='b.asp';this.form.submit()"
</form>