Boxes like Gateway's Destination are entertainment center-sized units that can serve as either a TV or computer. Because of their size, units like these are far better suited for viewing at a distance in a den or family room than for any typical desktop PC use. They're meant for shared use, not close work. The Destination approach hasn't exactly set the world on fire. I think part of the reason is high price, but also because PCs are personal devices, not group devices.
People assume the TV tuner is just for watching broadcasts.
The software also can use the closed-captioning stream to generate an instant transcript of news reports or shows in which you're interested. It's incremental, building on existing PC strengths, and delivers some really practical abilities in addition to purely entertainment features. As you probably know, by law all broadcast TV in the United States will switch to digital format during the next few years, and a handful of stations already have begun experimental digital-format broadcasts. This means that in the next five years or so, every TV now in existence will become obsolete. We'll all either need new digital TVs or adapters to allow our analog TVs to receive the new digital signals.