After a year of effort the Raspbmc team announced it has reached the 1.0 milestone. This means the team is confident they've achieved a stable port of XBMC specifically designed to run on the Raspberry Pi and the image is ready to downloaded for free and copied to your ready and able SD card. If you were already enjoying the fruits of the early builds of Raspbmc, you'll need to do a complete re-install but that shouldn't be too much trouble since you probably store your content on a network drive or external USB. Raspbmc 1.0 is based on the