Microsoft is still stumbling along. But PC troubles should trip it up eventually, unless new products catch on faster than they are today. The software giant late Thursday reported results for its fiscal second quarter ended in December. It said sales of the Windows operating system and Office software, Microsoft's two key profit drivers, increased 11% and 3%, respectively, versus the prior year and factoring in deferred revenue. That was despite a 6% fourth-quarter drop in world-wide PC sales, according to IDC. Microsoft can buck the PC trend a little while since some PC users still need to upgrade soon-to-be-unsupported versions of Windows. But 60% already have moved to the more-recent Windows 7, according to Microsoft, so those upgrades should slow before long. When that happens, touch-friendly Windows 8, the latest version, has to pick up the slack. But it isn't clear from the latest quarter, the first in which Windows 8 was available, whether it can catch on.