PDC/BDC

while installing windowsNT 4.0 server, there are 3 options

Stand alone ( member server )server
PDC
BDC

if i select , 1 st option, can i make that as a domain controller,

and if a windows NT4.0 server is running alrady ion a machine, howcan i find out, wheather it is a member server, pdc or BDC