Microsoft's new DIY kit for creating Xbox 360 and Windows games is now ready to rock.Available for free download from the company's site (see link below), it's strictly for developer professionals, as Stuff found out after installing and having a quick look around XNA Game Studio Express. If you were planning on knocking out a Chelsea-based version of Halo in half an hour, think again: you'll need to be fluent in coder language C Visual to make any headway.Right now, you can only create games for Windows, though there'll soon be an XNA Creator Club you can join to share your games on the Xbox 360. For the privilege of letting other 'XNA Creators' play your game, you'll need to reach in your pocket and pay 49 dollars for four months or 99 dollars for a year. Next year, there'll be a paid-for Pro version of Game Studio, designed to create proper, commercial games.Got the coding skills and the idea to match? Follow the links below.