Hi Alfredo,
it's really very simple. In the login page, I have the following:
<FORM method=post action="/register/user-login" name="login">
<script language="javascript" src="c:\machine\machine-name.js"></script>
The file c:\machine\machine-name.js on the client PC just contains the following line:
document.writeln('<input type="hidden" name="machine_name" value="BRIAN" />');
Then when the user logins and submits, on the next page (/register/user-login), I simply set a cookie to store the machine_name
ad_set_cookie machine_name $machine_name
I hope this is clear,
Brian