"Novice game creators can download the tool today from http://msdn.microsoft.com/xna to develop games for Windows XP and Windows Vista, at no charge. The games built on Windows can be migrated to the Xbox 360 console system starting this holiday season as part of the XNA Creators Club subscription for $99/€99 a year, or a four-month trial cost of $49, opening up retail console game development to anyone for the first time," says Microsoft.
There's also a FAQ which points out that you also need Windows XP SP2, Visual C# Express (on which XNA is based) and the latest DirectX runtime updates.
Comment: You can use XNA to write games and non-games programs for Windows XP -- whatever you like. You can't at the momnet write stuff for PocketPCs and Windows Mobile phones, though that may be added later.
The FAQ also includes:
Q: What does XNA stand for? A: XNA's Not Acronymed
Update: BBC columnist Bill Thompson is trying it out.
