Windows XP Professional x64 Edition is designed to meet the demands of customers who require large amounts of memory and floating point performance in areas such as mechanical design and analysis, 3-D animation, video editing and composition, and scientific and high-performance computing applications. Windows XP Professional x64 Edition runs on the AMD Athlon 64, AMD Opteron, Intel Xeon with EM64T, and Intel Pentium 4 with EM64T as the platform for customers who are reaching the memory limits of 32-bit systems. The key difference between 32-bit and 64-bit Windows XP-based computing lies in the 64-bit version’s ability to use much more system memory. Windows XP Professional x64 Edition initially supports up to 128 gigabytes (GB) of RAM and up to 16 terabytes of virtual memory. Physical memory support will grow in the future as hardware capabilities expand. Data in memory is accessed thousands of times faster than it is on a disk drive, offering a tremendous performance benefit for applications that are developed to use this greater system memory. Built on the Windows Server 2003 SP1 code-base, Windows XP Professional x64 provides increased reliability for business critical desktop computing. Users can now experience the stability and security of a server product on their PC. Windows XP Professional x64 Edition also includes the security features of Windows XP Service Pack 2 (SP2) providing better protection against viruses, hackers, and worms, and includes Windows Firewall, Pop-up Blocker for Internet Explorer, and the new Windows Security Center. With Windows XP Professional x64 Edition, users can confidently run their most mission critical applications with increased reliability, security, and performance.