HKCU\Software\Microsoft\Windows NT\CurrentVersion\
The PrinterPorts subkey lists the printers to which the client computer has a connection.
Each of the entries in this subkey has the following format:
printer-name REG_SZ Driver-name,Port:,Timeout
printer-name will either be local printer or \\server\printername.
driver-name for Windows clients will be winspool.
port will either be LPT1 or Nexx where xx is a numerical value starting with 00.
timeout is in the form of DeviceNotSelectedTimeout,TransmissionRetryTimeout.