Another general comment on your original bit of code...besides defining variables to use in place of direct values. You will want to include some sort of "deadband" into almost all of your drive code to account for the dynamic trim of the joysticks, prevent twitching/jerking, et cetera.
As somebody posted previously (sorry, I don't remember the name!), true neutral usually ends up at a value higher or lower than 127 (132 is quite common). To compensate for this fluctuation, we include a deadband of 6 in either direction, so "neutral" is really a range around 127.
Good luck!
