i've brought back pc from germany to malaysia and again from malaysia to germany.

from germany to malaysia, i carried it onboard with pc bag, got a few of scan that u have to pass and i imaging US will be more strick..

from malaysia to germany, cannot bring onboard again. The check-in people did't want the let me go with the pc onboard. Luckily i brought Box with me (i hide it first), packed it and put in cargo with 'fragile tag' .. arrive in working condition, but my water cooler system got crack on CPU heatsink..btw, i took out hdd and put it on my backpack..

here is my suggestion,
before you give ur pc/mac pro to airport crew to handle it, take out hdd, graphic card, ram and everything that attach to motherboard.This to avoid broken..then ask them to be really careful with ur pc/mac pro..ask for fragile tag..pack ur pc/mac pro nicely..

good luck..