On business trips I carry a laptop from place to place, always unpacking it, using it, and packing it again. I live in dread of forgetting one of its essential parts: the A/C cord, the mouse, the funny little edge connector that lets me access a LAN.
I've decided that the key thing is to pack the accessories first, and the laptop last. I can't possibly walk off with a practically empty case containing only the accessories, can I? Can I? (My wife smiles all too knowingly at this point ...)