I saw your post in response to the Halo 3 map pack sweepstakes, and I wanted to let you know that he's not totally screwed. He can actually still get his maps, he just has to go to his account management screen and look at download history, any download he started (doesn't have to be finished) will be in there, and he can prompt to redownload anything he's started in the past.
Hope that helps, if you've already figured it out then I guess you can ignore this.
saw your comment on the mythic mack pack giveaway forum about your friends failure to download the maps and personally your both idiots he can easily go to account management hit dl history and dl it again....fail.