IDC and Gartner have come out with their latest Q3 rankings of the world’s PC manufacturers, which means it’s time for us to do some dissecting. Not much changed at the top of the heap, where, according to IDC, HP still rules the roost with about 18 percent market share (despite that whole PC thing). But the most dramatic shift came from Lenovo, which scurried past Dell for second place, with 13.7 percent market share (13.5, according to Gartner) — a 36.1 percent jump from the the third quarter of 2010 (25.2 percent, says Gartner). Dell’s pie slice, on the other hand, shrunk slightly to 12 percent this quarter, down from 12.6 percent last year. On the global scale, meanwhile, PC sales increased by about 3.6 percent compared to Q3 2010 (3.2 percent, in Gartner’s books), though both research firms acknowledged that this figure was well below their respective projections. Why? IDC points to several economic factors, including the threat of a double-dip recession, while Gartner blames the rise of “non-PC devices,” including tablets. Surprise!