source: (xbox.com)

Downloading this gamer picture casts your vote and enters you in the Doritos® Unlock Xbox® Contest Vote & Win Sweepstakes. Winning an Xbox a day can only be done by voting on unlockxbox.com and Halo® 3 prizes by voting on Xbox Live®. Sweepstakes is open to legal residents of the 50 US or DC who are 13 years of age or older and in the state of Maine the Sweepstakes is only open to participants who are 18 years of age or older at time of entry. You must be 17 years of age or older to claim your Halo® 3 prize. NO PURCHASE NECESSARY. Starts: 12:00 p.m. CT on November 29, 2009. Ends: 11:59 p.m. CT on December 31, 2009. For full details, see Sweepstakes Rules & Eligibility at: http://www.unlockxbox.com/sweepstakes/srules.aspx