Authentication

Hello, I have a Windows 2003 server running DHCP, DNS, and acting as a Domain Controller. In our working environment we have over 100 computers, in which about 70 percent are pcs and 30 percent Macs. All my windows machines are running xp and they all authenticate through the Windows 2003 server. I recently acquired an X Serve, and the question is: Can the Macs authenticate through the Windows 2003 Server or can I settup the X Serve just to act for authentication. I would not want the X server to act as DHCP, DNS or DC, I just want the Macs to authenticate so users are a little bit restricted. If there is a way to do this can anybody help. I a newbie to Mac world. Thanks