Thanks for the heads-up! I had no idea they took away the dadgum pre-order credit...
A heads up for anyone who pre-ordered the game from Amazon. While they've taken away their $20 pre-order credit, several guys from AVS have had luck just getting in touch with their Customer Service and asking for said credit and having the $20 taken right off the top of Black Ops. They did this for me when I called with a legit reason for them to do so, and a few others decided to give it a whirl and (to the best of my knowledge) most have had success.