The rate in the bootloader determines the rate at which a new program is uploaded right?
Yes, this is the baudrate for the upload at the ATmega UART pins.
In the files boards.txt, once again the 168 chips are set to 19200 and the 328 chips to 57600, but the BT is also set to 19200.
This is the baudrate which avrdude uses for the PC serial port. As already mentioned, for the virtual Bluetooth serial ports this baudrate doesn’t matter. For FTDI USB serial ports, it has to match the UART baud rate of the ATmega.
Why is this?
I don’t know
You can change it to 115200 baud if you feel better, but as said, it doesn’t matter.
Is this where my computer must match the bootloader to work?
For FTDI USB Arduinos: yes. For the Arduino-BT: doesn’t matter.
If you make changes to the boards.txt do they take effect right away?
You have to restart the Arduino-IDE to reload “boards.txt”.
When setting “upload.verbose=true” in “C:\Documents and Settings<username>\Application Data\Arduino\preferences.txt”, you can directly see what settings are used:
-CE:\arduino-0017\hardware/tools/avr/etc/avrdude.conf -v -v -v -v -pm168 -carduino
-P\\.\COM21 -b19200 -D
-Uflash:w:D:\Documents and Settings\michael\My Documents\Arduino\Boduino2\applet\Boduino2.cpp.hex:i
avrdude: Version 5.8cvs, compiled on Nov 6 2009 at 22:28:43
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2009 Joerg Wunsch
System wide configuration file is "E:\arduino-0017\hardware/tools/avr/etc/avrdude.conf"
Using Port : \\.\COM21
Using Programmer : arduino
Overriding Baud Rate : 19200