Update: The promotional site for the offer has been reactivated, providing more details. Apparently, only original Xbox owners who have a current Xbox Live account and migrate their subscription to a new Xbox Live Gold membership after purchasing an Xbox 360 during the specified period will be eligible.

Original Xbox Live subscribers with an active account as of as of November 20, 2007, will be considered eligible. Though it's an online promotion, it's also only valid for subscribers living in the United States.

Original story: Want a copy of Bungie's Halo 3 for free? Microsoft will apparently be giving free copies of Halo 3 to anyone in the U.S. or Canada who purchases an Xbox 360 between November 21 and December 21, according to a page spotted by Evil Avatar on the official Xbox site that was quickly taken down.

The registration site for the offer is still up, requiring buyers to log in with the Windows Live ID linked to their gamertag. The site requires a valid Xbox 360 serial number and instructs applicants to enter the code XBX7777 on the online form.

Unfortunately, interested parties may have to wait until after Christmas to join their Halo 3-playing friends, as the site says Microsoft will ship out the games by January 18. Shacknews contacted Microsoft for comment, but has not yet received a response.