"Unfortunately, it seems clear that the Windows 8 launch not only didn't provide a positive boost to the PC market, but appears to have slowed the market," IDC Vice President Bob O'Donnell said.
The newest version of Windows is designed to work well with touch-sensitive screens, but the displays add to the cost of a PC. Together, the changes and higher prices "have made PCs a less attractive alternative to dedicated tablets and other competitive devices," O'Donnell said.
First-quarter shipments of PCs fell 14 percent worldwide from the same time last year, according to International Data Corp. That's the deepest quarterly drop since the firm started tracking the industry in 1994. Another research firm, Gartner Inc., pegged the first-quarter decline at 11 percent.