I'm making my own board and using an ATmega 328 with the Arduino bootloader. I have a DIP switch to select either an FTDI chip (for programming) to be connected to the ATMega's Rx and Tx, or a GPS that outputs serial to be connected. I was looking at this schematic for reference: http://arduino.cc/en/uploads/Main/ArduinoNano30Schematic.pdf
Why are there 2 resistors on Rx and Tx coming from the ATMega? Do I need those just for the connection to the FTDI chip, or do they need to be there for the GPS too?