Though eight years old, Windows XP still powers 71 percent of all PCs, according to a recent report from Forrester. That translates to millions of users that Microsoft must convince to upgrade to either Vista or the upcoming Windows 7.This has proven to be no easy task, especially in the enterprise sector. A high level of satisfaction with Windows XP from IT professionals combined with a down economy is keeping many from moving on. In a recent survey of 1,100 IT professionals from Dimensional Research, 72 percent said they are more concerned about upgrading to Windows 7 than staying with an outdated XP operating system. Yet the clock is ticking for Windows XP. The OS will soon move out of mainstream support to the extended support phase of its lifecycle, which means that IT managers will need to have a Premier support contract with Microsoft to get non-security fixes, and those fixes will come with a fee. Additionally, OEMs and system builders will only be able to obtain copies of Windows XP to preload on PCs until June 30, 2009. Benjamin Gray, analyst for Forrester Research, wrote recently in a research report called "Getting Ready for Windows 7" that "major independent software vendors are looking to phase out support for Windows XP later this year by adding support for Windows 7 early next year. Companies don't want to be caught running an operating system that is no longer supported by their vendors." Gray encourages companies to start planning now by either migrating to Vista as a bridge to Windows 7, or at least test applications and hardware for compatibility against Windows Vista -- which will ease eventual upgrades to Windows 7 because both operating systems are built on the same code base. The Forrester report reiterates previous warnings about the perils of skipping Vista, but it is one of the first reports to highlight specific features within Windows 7. Here are Forrester's top five Windows 7 features that IT managers need to understand now. DirectAccess: One of the most discussed enterprise features in Windows 7, DirectAccess, relies on Windows Server 2008 R2 and IPv6-over-IPsec tunneling and promises to keep users connected to the corporate network whenever they are online -- without the use of a VPN. The appeal to IT managers: they can better manage remote workers who will be connected to the network more frequently and be available for security patches and software updates. BranchCache: BranchCache will speed up access to remote files for workers in branch offices by caching a copy of files locally after the workers access them from the corporate network. The BranchCache feature is also dependent on Windows Server 2008 R2, and will come in two forms: a local cache hosted on the server or on branch PCs running Windows 7 directly.