Program the Arduino

You can use the source code or HEX file to get the software on the Arduino. Below a description of both approaches:

1. Using the source and the Arduino IDE

The Arduino code uses the Arduino-IRremote library to translate the bytes into IR-signals. To program your Arduino Nano, download and install the Arduino IDE. Follow the instructions on the Arduino-IRremote page to install the library. Get the Arduino source code files for this project from the repository. Build and upload the software to the Arduino.

If you receive the following error during code compilation:

In file included from Arduino.ino:17:
MagicRemoteIrCommunication.h:12: error: 'IRsend' does not name a type

You must remove the folder RobotIRremote from C:\Program Files\Arduino\libraries\ or C:\Program Files (x86)\Arduino\libraries\.

2. Using the precompiled HEX file

Instead of following the steps above, you can also directly upload the precompiled HEX file to the Arduino Nano (ATmega328). Use the command line tool AvrDude for that. There is a GUI wrapper available for AvrDude: XLoader. Make sure to choose 'Duemilanove/Nano(ATmega328)' as the device.

Alternative USB - serial port driver

I bought my Arduino Nano from a Chinese store. Instead of using the FT232R chip, it uses a CH340. You can download the driver from the website of the manufacturer:
http://www.wch.cn/downloads.php?name=pro&proid=5
(Google translation)