Each week Ross Rubin contributes Switched On, a weekly column about the future of technology, multimedia, and digital entertainment:

Microsoft is determined to figure out how to sell people their nth computer. Today, its ideal consumer's computing inventory looks something like this -- a couple of desktops around the home, a notebook for those mobile jaunts, a Media Center PC for controlling the television experience serving up Windows Media files to an Xbox 360 or lesser Media Center Extenders, and at least a Windows Mobile Pocket PC or Smartphone device.