Microsoft is trumpeting this figure as proof that adding Facebook, Twitter and Last.fm to the Xbox 360's Live hub was a huge success in its ongoing battle with Sony's PlayStation 3 and the Nintendo Wii.
There are currently around 20 million users of the Xbox Live service, and around 500,000 of them created Last.fm accounts in the same seven-day period, listening to 120 million hours of music.
See also: Microsoft Xbox 360 Elite
Numbers of people who used Twitter via their console are harder to come by, which suggests that they may not be as impressive.
Speaking to Gamesindustry.biz, Microsoft's Neil Thompson said of the early success: "It's just about giving people choice and giving them a slightly different experience.