boh! guarda se può andare:

codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>Pagina senza titolo</title>
<script language="javascript" type="text/javascript">
// <!CDATA[
var dati_modificati = false;
function window_onload() 
{
	for (var i = 0; i < document.forms[0].length;i++) 
	{ 
	    var tempobj = document.forms[0].elements[i]; 
	    if(tempobj.attachEvent)
		    tempobj.attachEvent("onchange", function(){self.dati_modificati = true;document.getElementById("Submit1").disabled = false;} );
	    else if(tempobj.addEventListener)
		    tempobj.addEventListener("change", function(){self.dati_modificati = true;document.getElementById("Submit1").disabled = false;}, false);

	} 

}




function form1_onreset() 
{
    dati_modificati = false
    document.getElementById("Submit1").disabled = true;
}

// ]]>
</script>
</head>
<body onload="return window_onload()">
<form id="form1" action="?" onreset="return form1_onreset()">
    <textarea id="TextArea1" cols="20" rows="2"></textarea>
    <input id="Text1" name="Text1" type="text" />
    <input id="Checkbox1" name="Checkbox1" type="checkbox" />
    <input id="Radio1" name="radio" type="radio" />
    <input id="Radio2" name="radio" type="radio" />
    <hr />
    <input id="Submit1" type="submit" value="submit" disabled="disabled"/>
    <input id="Reset1" type="reset" value="reset"  />
</form>
</body>
</html>