Get Windows login

Hi!

I was given a task to develop a php based application. All well, but
now my boss wants me to make it more "user friendly" in a manner that
they won't have to write in their usernames and passwords, which they
already have too many.

I figured, that I might be able to solve it, if I could somehow get
windows login, but my atempts to find an apropriate function were
unsucessfull.

Someone suggested the use of WinBinder to a similar question somewhere
else, but reading through documentation, I couldn't find what I was
looking for. I also found posix_getlogin(), but it appears not to be
available on Windows platform. If I try the get_current_user();
function, the return value is SYSTEM... Can I somehow work with
$_SERVER["REMOTE_USER"] perhaps? If I try it, the return is empty (or
at least echo returns nothing).

I'm developing under WinXP, Apache 2.2, PHP 5.2, however after I
finish, it will be on Windows Server 2003 Standard edition... The
company does use Active Directory, but I had no idea what PHP LDAP
functions manual was talking about, so if it's possible, I'd rather
avoid it.

I know this question is a bit futile to ask, since noone wants his
login to be visible to just any site, but any comments on the subject
would still be greatly apretiated.

Best regards,
Lado