Research firms Gartner and IDC have come out with their quarterly look at the PC market in the US and worldwide. With some exceptions, the results are not good. Only three companies, Lenovo, Apple, and to a lesser extent, Toshiba, posted gains for PC sales in Q1. The two reports differ on how large the decline in the total market is, and also on the cause. Is it tablets? Lack of innovation in PCs? Or just a lingering hangover from big Q4 spending? See all the numbers after the cut.