if you only one pc , it is not necessary to take nt server as a domain server, domain server can control all pc in the doman .in a domain , it can only have one primary domain server , but can have some secondary doman server and many common servers . you should select nt as a common server . nt server have some services which is not in nt workstation.(for example nt server has IIS , nt workstatin only has PWS) , if you do need a domain server , you must setup it as a primary domain server if you only one pc . and check the network card and protocol are installed and configures right .
if you have not a network card , you can install a MS loopback network card as if you really have a network card , but you can not communicate with other pc.