For all the stories about enterprises holding off on Windows 7 deployments, Windows XP's dominance in the enterprise is at the beginning of the end, says one industry analyst.This will not happen overnight, writes Forrester analyst Benjamin Gray in a new research report, but there are enough reasons for IT managers to "shake the status quo, and finally end Windows XP's corporate reign."XP, now an eight-year-old OS, "has delivered the compatibility, security, and reliability that firms had hoped for and to this day remains the desktop standard for most businesses and government agencies," Gray writes.Windows 7 Bible: Your Complete Guide to the Next Version of WindowsIndeed, Windows XP still powers almost 80 percent of commercial PCs, according to a survey of 665 IT decision-makers that was part of the Forrester report entitled "Windows 7 Commercial Adoption Outlook."Nevertheless, many factors point to XP's demise.Two-thirds (66 percent) of the 655 surveyed IT decision-makers from North American and European enterprises and SMBs are planning to migrate to Windows 7 eventually, although most don't have firm plans yet.Additionally, the research shows that 51 percent of respondents plan to have Windows 7 as the primary OS on their PCs within 12 months. Forrester also urges that companies should prepare for employee requests for Windows 7 as it becomes more popular with consumers.Here are five other key factors that Forrester believes will loosen Windows XP's grip on the enterprise and make way for Windows 7.Businesses Are Supporting Old InfrastructureForrester's Gray writes that because of the recession, IT managers needed to lower costs by extending the life of existing desktops and laptops. Many also held off on hardware upgrades because they wanted them to coincide with a Windows 7 deployment. For global companies that support thousands of apps, compatibility testing can take up to 18 months. So if they've been testing in anticipation of Windows 7's release, full deployments will conclude by the end of 2010.\nWindows XP Support Is WaningSince April of this year, Windows XP SP2 has been in the extended support stage, which means support is no longer free and only includes security updates and patches. Next July, XP SP3 will enter extended support as well. All support for Windows XP SP2 and SP3 will end in April 2014.\nWindows XP Availability Will Get PinchedThe ability to buy Windows XP machines will change after Windows 7 becomes generally available this week, Gray writes. With the release of Windows 7's first service pack, scheduled to be a year or so after its initial release, OEM licenses bundled with every PC will no longer have downgrade rights to XP.This means that to deploy Windows XP on a new PC, companies will have to purchase volume license copies of Windows along with the new PCs or use existing, unused Windows volume licenses.Business Reasons Encourage Upgrade to Windows 7Forrester has found that the enterprise features in Windows 7 will help companies improve networking and security and ultimately cut costs. Some features that Forrester recommends IT departments prepare for include: DirectAccess, which lets remote workers connect to corporate networks without the use of a VPN; BranchCache, which speeds up access to networks in remote offices that are away from corporate headquarters; BitLocker To Go, an extension of the BitLocker hard-drive encryption feature introduced in Vista that will now protect removable devices like external hard drives and USB thumb drives; AppLocker, which aims to protect users from running unauthorized software; and federated search, which promises to simplify access to data across local and remote networks.\nImproved Client Virtualization Can Accelerate Deployment PlansWindows 7 ships with Windows Virtual PC and Windows XP Mode, which provide the ability to run apps not yet compatible with Windows 7 in an XP-compatible virtual machine. Moreover, customers with software assurance agreements can use MDOP (Microsoft Desktop Optimization Pack), a subscription-based suite of apps that includes virtualization technologies allowing IT pros to deploy and manage virtual images, "thus removing the last barriers to deploy Windows 7," writes Gray.Shane O'Neill is a senior writer at CIO.com. Follow him on Twitter at twitter.com\/smoneill. Follow everything from CIO.com on Twitter at twitter.com\/CIOonline.