Microsoft CEO Steve Ballmer said during his keynote at BUILD today in California, that there have already been over 500,000 downloads for the Windows 8 developer preview which launched yesterday evening. The preview comes with the new interface, better desktop performance, and a new interface for tablets called Metro. MS also confirmed yesterday Xbox Live would be included with W8, with more details to be announced at a later date. The Windows 8 developer preview can be downloaded here. Thanks, Newowin.