[tHE DSS]

Supply abit more information on the structure of the two systems (gives an idea of an interface).

You can do this in any script :

PHP Code:

require ("path_to/global.php");
...
...
...
if ($bbuserinfo[userid] == 0) {
    // not logged in or un-registered
} else {
    // registered and logged in
} 


... are the two systems on different servers though?