ciao kallo,

devi fare un controllo all'onkeyup sui due campi
codice:
<form method=post action=ricevi.php>
<p align="center">


        Email : 
        <input type="text" name="EMAIL" size="38" 
                     style="border-left-width: 0; 
                            border-right-width: 0; 
                            border-top-width: 0; 
                            border-bottom-style: solid; 
                            border-bottom-width: 1"
        onkeyup="this.form.Conferma.disabled=!(this.value!=''&&this.form.PIN.value!='')">


            PIN :
        <input type="password" name="PIN" size="38" 
                     style="border-left-width: 0; 
                            border-right-width: 0; 
                            border-top-width: 0; 
                            border-bottom-style: solid; 
                            border-bottom-width: 1"
        onkeyup="this.form.Conferma.disabled=!(this.value!=''&&this.form.EMAIL.value!='')">
</p>
<INPUT type=submit value="Conferma" name=Conferma disabled>
</form>