Promising technology, or technology without promise? That's the question with any "touch" computer that relies on a "natural user interface" (NUI), hoping to make the mouse a distant memory. About 18 months ago, HP released the first TouchSmart to a mild but interested reception. Now, the new 22-inch all-in-one IQ506 model is a second attempt: It has better touch features, a bright and vivid display, sleek accessories, and a new touch interface. But is it a worthwhile desktop computer?