FTDI Basic Breakout - 5V
As Joby Taffey suggests, the rx &amp; tx pins of the AVR are 2 &amp; 3 respectively, but on the Arduino headers they are pins 0 &amp; 1. You also want to connect DTR to the reset pin of the arduino to enable automatic programming.

  FTDI        Arduino
Breakout        (5V)

     GND &lt;--&gt; GND
     CTS &lt;--&gt; (not connected)
      5V &lt;--&gt; 5V (if you want the breakout to power the arduino)
     TXO &lt;--&gt; RX (pin 0)
     RXO &lt;--&gt; TX (pin 1)
     DTR &lt;--&gt; RESET (possibly through a 100nF cap*)


On the FTDI TTL232R cable, DTR is not present so you have to manually reset the board before flashing. By default the Arduino will stay in the bootloader for 6-8s, but some boards rely on the automatic reset and have much shorter timeouts (0.25s say). For these boards, set upload.verbose = true in your Arduino conf file, and learn to time the reset the moment the software attempts to flash the board.

* Arduino Wiki