Connection paramters for Arduino Boards

COMx = COM-Port, e.g. COM1

Pro Mini:       avrdude -c arduino  -p m328p -P COMx -b  57600
Duemilanove:    avrdude -c arduino  -p m328p -P COMx -b  57600
Uno:            avrdude -c arduino  -p m328p -P COMx -b 115200
Mega:           avrdude -c arduino  -p m1280 -P COMx -b  57600
Mega2560:       avrdude -c wiring   -p m2560 -P COMx -b 115200
Arduino as ISP: avrdude -c stk500v1 -p m328p -P COMx -b  19200

On problems with the Mega2560 under Windows run the following command before avrdude (at best with a .bat file). This triggers a reset and starts the bootloader.

mode COMx dtr=on or or avrdude -c arduino -p m2560 -P COMx