If you set the server up as a Dedicated server you only require one NIC that nic communicates with the workstations on the network. Since the server used a non routeable IP example: 192.168.1.1 It can not be seen or accesses from the internet unless it is setup up for VPN access. If you want Internet access you can setup another server that acts as a firewall and Internet server. The second server would have 2 NICs one to interface with the outside world using a routeable IP, the second, NIC would also use a non routeable IP i.e. 192.168.1.2 The server connected to the outside world could be used just as a web server and mail server. The internal one just as a file server and print server. This would level the load especially if you were hosting 8 or 10 virtual domains on the web server.