Since Xbox Media Center is not an officially licensed software application for the Xbox, it requires that the the Xbox is "modded" to permit the code to run. Typically, modifying the Xbox is done either (1) by physically modifying the motherboard by soldering some connections and adding a mod-chip, (2) applying a software patch (aka "softmod", see the 30 min. softmod tutorial for instructions), or (3) swapping the Xbox hard drive ("hot swap"). Note that none of that is required if XBMC is being installed on a PC, Mac, or Linux computer.
XBMC is a free, open-source application distributed under a GNU General Public License.Xbox Media Center won two categories at the SourceForge 2006 Community Choice Awards: 1) Best Multimedia Project, and 2) Best Game Project. It is nominated as a finalist in six categories for the 2007 awards. The non-Xbox versions can be downloaded at XBMC's official website.