Microsoft's new Windows 7 OS, which is due for release on Oct. 22, will not be a major factor in the recovery of PC shipments, Shiffler said. On Thursday, Microsoft said that it planned to let people who buy PCs with Windows Vista starting this Friday upgrade to Windows 7 for free, once it becomes available in October.

"People aren't going to buy a new PC because of a new operating system," Shiffler said. Microsoft could try to counter the PC slowdown by launching a campaign to show that the OS is offering something new in PCs, but that may still not get consumers to spend on the OS, he said. Enterprise users will put off adopting Windows 7 for at least a year until all the kinks of the OS have been ironed out, he said.