This is the right way! but check "ipenabled" criteria of the NIC
newIP[ "IPAddress" ] = IpAddresses.Split( ',' );
newIP[ "IPAddress" ] = IpAddresses.Split( ',' );
newIP[ "SubnetMask" ] = new string[] { SubnetMask };
setIP = mo.InvokeMethod( "EnableStatic", newIP, null);