Thin is in again, at least for a spell, as hardware makers use Linux to sell companies on the idea of forsaking full-fledged PCs in favor of stripped-down "thin clients." In the 1990s, Microsoft foes Oracle and Sun Microsystems advocated, with little success, using thin clients that they called the Network Computer and Sun Ray, respectively. The sales pitch--that it's cheaper to leave the heavy lifting to central servers and avoid the management and security headaches of PCs--hasn't yet won over the masses. This week at the LinuxWorld Conference and Expo, thin-client sellers used Linux to spruce up their offerings....