codice:
<HEAD> 
<script> 
function cambia() { 
y=document.mioform.radioB;
for(i=0;i<y.length;i++){
   if(y[i].checked)document.forms["form"+i].style.visibility='visible'
	 else document.forms["form"+i].style.visibility='hidden';
	 }
} 
</script> 
</HEAD> 
<BODY> 
<form name="mioform"> 
<input type=radio onclick="cambia()" name=radioB checked>Milan
 
<input type=radio onclick="cambia()" name=radioB>Roma
 
<input type=radio onclick="cambia()" name=radioB>Lazio
 
</form> 

<form name="form0" style="position:absolute">
<input type="text" value="dagfaagd">
</form>

<form name="form1" style="visibility:hidden;position:absolute">
<select><option>adsdasdas</option><option>adsdasdas</option></select>
</form>

<form name="form2" style="visibility:hidden;position:absolute">
<textarea rows="20" cols="20">
safsafawf3wccewc
</textarea>
</form>
</BODY>
ciao