THE GROWTH OF PCs will slow over the next two years because of a lack of a "killer app". According to analysts Gartner although PC sales are booming at the moment as company"s replace ancient kit, that could all change in a couple of years. It predicts that sales will slow to a trickle because there will be no need for upgrades. The villain of the piece? Step forward Microsoft for not being fast enough with Longhorn, says Gartner analysts.