Login into windows through Linux.

Sir,
I would like to know that can I log into our domain which is on NT Server through Linux, mean to say that Linux should act as a PDC and Nt server should act as a BDC. Presently all our users login into NT Server domain. Please tell me how should I make the users Login into Linux and Linux sends to NT Server for authntication. I just know that a Linux box should be running Samba Server. Please tell me more what to do? Reply,
Manish.