Personally, I recommend that Windows XP users switch to Windows 7 (and avoid Windows 8) or OS X, but that's not so easy for home users. Many stick with what they know and that works for them as is. If you're still using Windows XP as a home user, you're not a power user and you're not a geek who wants to use the latest whatever. The very act of relearning how to use the computer is a major turn-off. Yet that's what Windows 7 requires, and Windows 8 takes that required relearning to a horribly high level given its awkward mishmash of two operating systems. Sorry to say, Windows 8.1 doesn't fix that fundamental flaw.
Unfortunately, you can't go to a store and buy a Windows 7 PC, and getting one online is not so easy, either. Thus, people stay where they are. Or they buy an iPad or other tablet instead, relegating the PC to a family terminal for occasional school and work use (Microsoft Office works just fine on XP!).
Microsoft understand this "stay put" mentality is strong, which is why it now says it will no longer offer its free Microsoft Security Essentials (MSE) antivirus product to XP users as of April 8. The threat is clear: Switch or get infected. Such a lovely customer strategy! Fortunately, many other antivirus tools are out there, and in any event MSE is hardly that effective to begin with.
Enterprises used the Vista debacle as an excuse to prolong the lifetimes of the PCs they buy, reducing how often they replaced PCs. After all, PCs last a long time these days, so why toss them? Then the recession hit, and enterprises deferred Windows 7 and associated PC replacements.
Finally, they're now spending (some) money on new PCs, and to avoid the high cost of supporting users' confusion around Windows 8, not to mention avoiding the higher costs of touchscreen PCs that Windows 8 favors, they're deploying Windows 7. PC makers are getting some sales, and Microsoft is getting license renewals, but PC makers aren't selling the higher-margin touch and hybrid models, and Microsoft isn't selling additional Windows 8-oriented server options. Did I mention that Microsoft Office works just fine on XP?
Also, many enterprises have XP PCs they can't easily replace. In the 2000s, many software developers in enterprises and in specialty-application shops tied their software to Microsoft's ActiveX tech to run through the Internet Explorer browser. These ActiveX ties are typically version-specific, and ActiveX in turn is tied to a specific IE version. There's a similar tie-in in some Java versions as well, as Microsoft applied the same strategy to that platform. The XP compatibility mode in Windows 7 and 8 is supposed to address this legacy tie-in, but it requires both IT overhead and newer PCs, so there's a high cost.
As a result of the Microsoft lock-in strategy, many companies have apps they rely on and would cost too much to change that run only on a XP PC and an older version of IE. Microsoft wanted that tie-in, of course, to ensure that enterprises couldn't leave Microsoft even if apps moved to the Web on other OSes or even on other browsers, which was its fear at the time. The lock-in worked a bit too well!
This anchor is Microsoft's fault, and it hasn't really helped companies address it, XP mode nothwithstanding. Yes, IT should have long ago replaced those apps with platform-neutral technologies, but that's not the IT way -- too many relish being "Microsoft shops" and have now become Stockholm Syndrome hostages. Plus, few business execs would be willing to pay the cost of replacing the apps bought under this foolish strategy, so it's hard to even ask.