Microsoft is offering a free copy of Halo 3 to all new Xbox 360 purchasers this Christmas... though you'll have to already have an original Xbox and current Xbox Live account (is anyone actually playing Xbox Live on the original Xbox any more?).
Original Xbox Live subscribers who purchase an Xbox 360 and migrate to Xbox Live Gold (that's the 360 paid version) between November 21 and December 21, then register on this website (phew!) will get sent a copy of Halo 3 by Microsoft.
It's currently only open to North American customers and even they won't be able to finish the fight until January, when Microsoft sends the copies out.
We've been on the case with Microsoft's UK op, which was unavailable for comment at the time of writing, but anyway hasn't anyone who cares already got Halo 3 already?