the one that i found on google is that one http://www.extremeelectronics.co.in/avrtutorials/images/rs232_sche.GIF
the arduino tutorial say:
1 capacitor between 1 - 3
1 capacitor between 1 and ground
1 capacitor between 4 - 5
and 1 between 6 and ground
the on o googles tutorial say
1 capacitor between 1 - 3
1 capacitor between 2 and vcc
1 capacitor between 4 - 5
and 1 between 6 and ground
and 1 more between vcc and ground
i tried both ways with the same result =(
the arduinos tutorial also say to jump all the unused pins to vcc. the google one just say to keep it non conected.