because I'm borderline retarded, I have a new 20GB HDD now on the machine. I kept a "spare" around in the event of this happening. I'm currently redownloading about 1.3TB's of Halo 3 Map data.
This is taking for fucking ever.
I recovered my gamertag on the new HDD. This had better allow me to play this DLC across all screen names, not just the one I purchased it with.