User 7wed ran into a problem with SoftwareSerial.
He solved it by using an other Serial Terminal program, but the problem with the library still exists.http://arduino.cc/forum/index.php/topic,162529.msg1216298.html#msg1216298
I can confirm this error.
My test was with a CP210x usb-to-serial to the SoftwareSerial port on the Arduino.
When using HyperTerminal to send characters, every second byte is incorrect received by the SoftwareSerial library. I used an Arduino Uno. Changing pins, or using 9600 baud does not solve it.
Sometimes the characters are received correct if typed slow. When using autorepeat (keeping the button down) will make every second byte wrong.
HyperTerminal transmits the data as soon as typed in the keyboard. I used the version that came with Windows XP. The settings are without flow control, 8 bit, no parity, 1 stopbit, and I tested 2400 and 9600 baud.