No need to remove the microcontroller chip or add jumper if you are just using the Arduino board for serial communication (that is, you are not using the on-board ATMega328P).
I disagree. Everytime the Arduino board is powered up it will jump into the bootloader and twiddle with the serial pins. This could 'confuse' the external device or PC that are using the serial link. Best to disable the AVR chip.
Lefty