When Microsoft announced the Media Center edition of Windows XP, it was in some ways the desktop counterpart to the Tablet PC mutation. Whereas the Tablet PC was envisioned as a new form factor for notebooks, Media Center held the promise of transforming the desktop into its own new form factor. Indeed, in one of Bil Gates's final CES keynotes promoting innovative PC designs, he didn't mention desktops at all, referring to stationary computers as "entertainment PCs" in an AV component style.
But while a few companies continue to sell Media Center PCs explicitly designed for connection to a television -- among them Sony, Alienware, and companies targeting custom installers such as Niveus Media, the form factor hasn't taken off for a variety of reasons. Microsoft, in turn, has focused more on Media Center Extenders such as the Xbox 360 and HP MediaSmart Connect to bring the Media Center experience to the big-screen TV. And despite some technological improvements coming to help the cause, that situation is unlikely to change dramatically.