The script in the RS-232 tutorial in http://arduino.cc/en/Tutorial/ArduinoSoftwareRS232 has timing problems.
I have tried it with Arduino UNO, Leonardo and MEGA2560 with Windows hyperterm and Linux Gtkterm.
The original script produces garbled chars in any case
The correct timings are in Serial Communication Basics
You have to change the script according what follows:
// old values
//#define bit9600Delay 84
//#define halfBit9600Delay 42
//#define bit4800Delay 188
//#define halfBit4800Delay 94
//new values: tested on Windows with hyperterm and Linux with Gtkterm on Arduino UNO, Leonardo and MEGA 2560
#define bit9600Delay 100 //theoretically 104
#define halfBit9600Delay 50 //theoretically 52
#define bit4800Delay 208
#define halfBit4800Delay 104
The correct timings were tested on Arduino UNO, Leonardo and MEGA 2560.