NOT SO, NOT SO
Do not think that you will protect other outlets by simply replacing one
of the outlets. It is also not just a matter of placing the ground
fault device at "the front of the line". The ground fault device will
only protect other circuits if they are wired through the ground fault
device properly. Read the instructions that come with the ground fault
device.
To protect entire circuits, ground fault breakers are also availiable.
Installation is simple, if one can follow directions.
Be safe.
Jeff