For the Mac, like the PC, it's all downhill from here

For the last five years, Mac sales have grown faster than PC sales, and even as PC sales declined in the last several years, Mac sales kept growing. They reached between 10.5 and 11.8 percent of US PC sales in 2012, depending on whether you believe IDC or Gartner. That's the highest proportion Apple's Mac has achieved for several decades and a remarkable return from its death's-door days in the late 1990s.

But something flipped this time around: Apple reported that Mac profits are down 7 percent versus 2012. Mac sales slid 11.2 percent and PC sales were flat (if you believe IDC) or Mac sales dropped 2.3 percent as PC sales rose 3.5 percent (if you believe Gartner). Either way, Macs are no longer growing faster than PCs, and, in fact, PCs are now outpacing Macs.

iPad sales are leveling off -- a large percentage of homes have at least one, and cheap Android tablets are filling the same demand for lower-income households and countries. Tablet sales to businesses have also flattened, notes 451 Research analyst Chris Hazelton, now that those business users that benefit from using iPads have them. Meanwhile, PC sales appear to be up mainly due to business sales, a consequence of all those PCs running Windows XP finally being converted to Windows 7, which often means getting a new PC. What we're seeing in the Windows world is what Wall Street calls a dead-cat bounce, not a revitalization of the PC market.