Over 15 percent of midsize and large enterprises will still have Windows XP running on at least 10 percent of their PCs after Microsoft ends support for the operating system and also for Office 2003, in April 2014.
According to Gartner, not having support means that organizations' PCs could be vulnerable to attack.
This is particularly the case for any unpatched device, even if it is only a private network and has no internet access, the Enterprise Innovation reports.
The report also pointed out that many applications would no longer be supported while running on Windows XP.
Michael Silver and Steve Kleynhans, VP in Gartner's client computing team, recommendations for organizations that believe they're unlikely to complete their migration projects by April 2014 should prioritize their applications and users so that they can reduce the risks by addressing critical resources first.
Gartner defines a critical application, or its user as one where if the application fails or the user can't do his or her job, there could be financial or legal consequences.
Kleynhans said organizations must conduct several analyses on their application portfolios to help safeguard the organization after XP support ends, and in preparation for Windows 7 or 8 migrations.