Halo 3 on Legendary finished ... for real

Phew.  :)

As hoped, finishing Mission 7 on Legendary (for the second time, ahem) did the trick: I got the hoped-for "2 for 250" achievement pop-up. (You get credit for finishing it on Heroic too; they're each worth 125 points.)

Now I can never, ever play that game again, at least the single player campaign.

On to multiplayer...