The WINS tab gives you the option of enabling LMHOSTS lookup in addition to NetBIOS over TCP/IP either using DHCP or directly. The client will first check it's cache, then WINS, then Broadcast, then the LMHOSTS/HOSTS, then DNS. I've never heard of NetBIOS on TCP/IP, I'm not even sure that's real. The mechanism in Windows is NetBIOS over TCP/IP. The security risk for NetBIOS being enabled is minimal while inside your protected LAN, but the concern is when it's unprotected. NetBIOS forces the computer to advertise it's name and any resources to the network. It also opens ports 137, 138 and 139.