How the freeradius-server can get username/password from Win2k-Se rver ?

Hi @ all, I'm a freeradius newbie and try that the freeradius(version 1.0.2) get their users (and passwords) by domain from the active directory. I googled a lot and found differend ways for this. (ntlm, pam-module). Which of these ways is the securest way? Are their any other possibilities? Are their any manuals/helps therefore or can someone discribe me how to implement this? thx schustn