"I expected a lightning move toward Baghdad with virtually no resistance."
You are a fool. You didn't expect snipers, ambushes, terrorist car bombings (still waiting for this), suicide attacks, mines, boobytraps, etc.?
The logistics situation is being blown totally out of proportion by the hysterical U.S. media. Weather has been the biggest drag on logistical operations, not armed resistance. Iraq has zero ability to BREAK our supply lines (lack of an airforce, lack of heavy armored units, and lack of heavy artillery in the south). The Iraqis CAN harass us with small arms fire, but this will have very little effect on the speed and scale of ground supply movements. As we've seen thus far, to fire on a convoy has been a death wish for many Iraqis.