Server running Windows 2003 Server
Macintosh client running OS-X connects to the Server via Remote DeskTop Connection
Macintosh client running OS-X connects to the Server via Remote DeskTop Connection
Macintosh client running OS-X connects to the Server via Remote DeskTop Connection
The Mac/Windows Connection:

If you prefer Macintosh computers, all you need to add is a server running Windows Server 2003 Server.

Attach your Macs via Remote DeskTop Connection.  This software is built in on the Mac OS-X operating system and part of the Windows 2003 Server operating system.

Easy to setup and it works great.