But tablets aren't the only reason the PC market has been in disarray. Desktop virtualization has also played a behind-the-scenes role -- and that's been bad news for not only PCs, but also for Windows 8.
Virtualization technologies such as virtual desktop infrastructure (VDI) have been around since long before the PC market began to decline. Typically, the concept has involved hosting a user's desktop session on a server, rather than on the user's local machine. Doing so has allowed companies to save money by avoiding the cost of a full license for each employee, and to improve security by giving IT more control and enabling the use of thin clients.
But thanks to the BYOD and mobility movements, virtual desktops are being harnessed in new ways.
[ Why aren't Windows 8 tablets selling? Read Windows 8 Tablets' Big Flaw: Hardware Compromise. ]
"The number-one driver for VDI has shifted from cost savings to supporting the ability to work from anywhere," Forrester analyst David Johnson said in an interview. "More companies are investing for a flexible work style."
For many companies, this investment has meant embracing BYOD. The shift has begun to affect PC sales in two ways. To start, it's turned many situations that once called for two computers into situations that now demand only one. In the past an employee might have a computer at home and a computer at work. But with desktop virtualization, a personal laptop can double as an office-ready BYOD device -- even if a worker wants to use a MacBook in a Windows office.
Second, it's also made tablets more viable as PC replacements. Many business applications, even popular ones such as Microsoft Office, haven't been translated to iOS or Android tablets, potentially limiting how easily users can ditch their PCs for a new tablet. Desktop virtualization diminished this limit, giving many users the excuse they needed to delay a PC upgrade.
Microsoft Office tops the list of desktop apps that are most commonly used on tablets, with Word, Excel, Outlook and PowerPoint ranking in the top 10, according to figures compiled by Splashtop, a maker of remote desktop products. Also on the list, which was generated by hundreds of thousands of remote desktop sessions from 14 million users, are various desktop browsers and media players.
Ironically, the rise in desktop virtualization is discouraging PC sales even as it testifies to the importance of PC software. The trend also raises an interesting question: If people like using tablets but sometimes need desktop software, why don't more of them use Windows 8, the only platform that combines both? According to research firm IDC, Windows tablets accounted for only 4% of the market in the most recent quarter.
From Microsoft's perspective, many of the potential explanations are disheartening. Windows 8's library of mobile apps has neither the depth nor breadth of Android and iOS's respective catalogues, so it's reasonable to infer that Microsoft simply hasn't delivered the apps that have made Android and Apple tablets popular.
Other key issues are user experience and accessible pricing. With Windows 8.1 and cheaper devices with better battery life on the way, Microsoft might be able to make strides -- but, as with most computing these days, it is the apps that are crucial.
Microsoft has been trying to improve Windows 8 adoption by declining to release Microsoft Office for Android and iOS tablets. But tablet-friendly alternatives to Office, such as Google Docs or Open Office, are becoming more capable, and some Office users have already shown that they'd rather use VDI than move to Windows 8.
If tablet users feel the same way about Windows 8.1, Microsoft will face tough questions about its tablet strategy.