Its funny, because I downloaded a Good Sidebar widget with Microsoft Download Center Updates, and I saw this:
http://msdn.microsoft.com/en-us/library/bb200104.aspx Its called XNA Game Studio 2.0, they have a 3.0 now, but this is the one that I came across.
Quote: Microsoft® XNA® Game Studio 3.0 is a set of tools based on supported versions of Microsoft® Visual Studio® tools that allow students and hobbyists to build games for Microsoft® Windows®, the Microsoft® Xbox 360® video game and entertainment system, and Microsoft® Zune®. XNA Game Studio also includes the XNA Framework, which is a set of managed libraries based on the Microsoft® .NET Framework® 2.0 that are designed for game development. This documentation collection contains technology overviews, tutorials, and reference material related to XNA Game Studio
You can be the next 360 Game Designer o.o