Remember, the *.P5K file is a binary image of the controller's program and tag databases that is stored on a CompactFlash card installed in the controller. There is also a *.bin file with the controller firmware and a *.xml file that describes the saved program to the controller.
These files cannot be opened by anything other than a the same model of ControlLogix or CompactLogix controller that created them.
I understand that future releases of RSLogix 5000 may include an image file decoder, but today there is no PC software method of opening those files.
When I ship out a loaded controller with a CompactFlash card, I also put the card into my PC's card reader and save the *.ACD and any .XC or .DNT files needed for the system onto other directories on the card, for exactly these sorts of reasons.