Windows Fundamentals for Legacy PCs is based on Microsoft Windows XP Embedded Service Pack 2 (SP2), enabling you to upgrade to the security and stability of the Microsoft Windows XP platform. This eases the transition to Windows Vista Enterprise when you eventually replace your computers.

Windows Fundamentals for Legacy PCs is not a general-purpose operating system. It is designed to work with the Microsoft Remote Desktop Connection client or third-party clients such as the Citrix ICA client. In addition, it allows for a limited number of workloads to be executed locally, including security software, management software, terminal emulation software, document viewers, and the .NET Framework.

http://www.microsoft.com/licensing/programs/sa/benefits/fundamentals.mspx

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