To celebrate the IMAX 3D release of Half-Blood Prince, which opens on the screens across the US tomorrow, the company has launched a contest for fans to win posters and t-shirts. To be in with a chance of winning go here, click on 'enter to win' and follow the sweepstakes link. Then fill in your details.

The contest is open to residents of the US and Canada that are age 18 or older. It closes on August 19th. Five winners will receive the posters and t-shirts. Winners will be picked on August 24th.

Source: The Leaky Cauldron