Unix in NT Domain Systems. Manish Patel

I run a QA Lab for startup company, Company has NT Server Domain systems. In the Lab I have 20 NT server and a PDC(w/ DHCP) & BDC and Exchange Server. I have two+ Sun boxes Ultra 160 and sun 420R Server.
1. How should i artchitec my Sun systems so they can be integrated into NT based Network system?
2. Does Unix have such thing as Domain like PDC and BDC?
My current configuration is for UNIX system are standalone, not part of my network or networked with each other. Thank You.