Microsoft said on Tuesday that it was making available over 400 pieces of downloadable content through the Xbox Live Marketplace, including interactive demos of games, as well as free and premium add-ons for games, movie trailers and music videos.

To serve the younger gamer, credit cards will not be required to purchase goods. Premium content will be paid through a new stored-value system called Microsoft Points. These points are available for purchase at retail locations and online through the Xbox Live Dashboard.

Using Microsoft Points, users will be able to purchase gamer pictures, themes, and even full game downloads from the Xbox Live Arcade, the company said.

The Marketplace will become available when the Xbox 360 console launches on November 22. Cards filled with 1,600 Microsoft Points are priced at $19.99 USD, or £17.50 for a 2,100 point card in the UK.

Themes that would personalize a user's Xbox 360 dashboard will cost 150 points, while pictures for gamer profiles run anywhere from 20 to 60 points each.

Games offered through the Xbox Live Arcade will follow a three-tier pricing structure of 400, 800 and 1200 points per game.

For 400 points, traditional tabletop games, classic arcade titles and other basic games will be offered. The next tier at 800 points will include some newer titles such as Bejeweled 2, Mutant Storm Reloaded, Outpost Kaloki, Wik: Fable of Souls, and Zuma. Finally, at the 1200 point level, only one game will be offered at launch: PrdixelStorm's Bankshot Billias 2.

Microsoft said it plans to offer the majority of games at a price of 800 points or less. Also, it will allow users to play each game once before they purchase the full version.

Pricing for any entertainment content on the Xbox Live Marketplace was not announced.