RFID shield and receiver compatibility

I have ordered the following items:

Both of these have female RS232 connections

My question:
Do I need a straight male to male RS232 cable like this

or a null (crossover) cable

I know that it goes tx to rx when you want to talk to the arduino and vise versa, but I don't know which adapter to get. Do I need to flip the signals going to the shield (use the crossover) or does the shield just want the signal as is (straight)?[/list]