Microsoft, the company that spent half a billion dollars on marketing for the Xbox 360 console, has announced that the marketing push for its version of Rockstar’s Grand Theft Auto IV will match that of its own Halo 3.

This unprecedented show of support for a third-party game appears to be a clear message from the House That Windows Built that it believes gamers with a choice between the upcoming Xbox 360 and PS3 versions of the game should choose the former.

Stephen McGill, Head of Gaming for Xbox UK, said, “We’re naturally very excited about GTA: IV coming to Xbox 360, we know pre-orders are going fabulously well and we know consumers are extremely excited about all the great things the Xbox 360 version has to offer.”

McGill’s comments refer to the exclusive downloadable content that will be made available to gamers via Xbox Live this autumn. Between this extra incentive and the higher number of Xbox 360s sold in comparison to Playstation 3s, many retailers expect the high demand to create software shortages.