Microsoft has today made XNA Game Studio Express version 1.0 available as free download. It allows game development for Windows and Xbox 360 platforms.
Requirements for XNA Game Studio Express are Windows XP SP2, DirectX 9.0c compatible graphics card and Visual C# 2005 Express Edition which is also available as free download from Microsoft. XNA development environment comes bundled with source code of Spacewar game which acts as a tutorial. Development of games with Live support is not possible at the moment, though.
In order to play self-made games on Xbox 360 XNA Game Launcher must be downloaded from Xbox Live Marketplace and gamer profile must have active XNA Creator´s Club subscription. These are available from Marketplace under Games category. XNA Creator´s Club subscription costs EUR 49,00 for 4 months or EUR 99,00 per year.
XNA Game Studio Express is available here. Coding games of your dreams can now begin!