Windows XP Professional 圆4 Edition also introduces Kernel Patch Protection (also known as PatchGuard) which can help improve security by helping to eliminate rootkits.

Uses the Windows Server 2003 kernel which is newer than 32-bit Windows XP and has improvements to enhance scalability.

As such, as of 2014, the OS supports all commercially available multicore CPUs, including Intel Core series, or AMD FX series.

Supports up to two physical CPUs (in separate physical sockets) and up to 64 logical processors (i.e.

During the initial development phases, Windows XP Professional 圆4 Edition was named Windows XP 64-Bit Edition for 64-Bit Extended Systems. Windows XP Professional 圆4 Edition is not to be confused with Windows XP 64-Bit Edition as the latter was designed for Itanium architecture. However, it includes client features of Windows XP such as System Restore, Windows Messenger, Fast User Switching, Welcome Screen, Security Center and games, which Windows Server 2003 does not have. Windows XP Professional 圆4 Edition uses the same kernel and code tree as Windows Server 2003 and is serviced by the same service packs.

Although the theoretical memory limit of a 64-bit computer is about 16 exabytes (17.1 billion gigabytes), Windows XP 圆4 is limited to 128 GB of physical memory and 16 terabytes of virtual memory. 32-bit editions of Windows XP are limited to a total of 4 gigabytes. The primary benefit of moving to 64-bit is the increase in the maximum allocatable random-access memory (RAM). It is designed to use the expanded 64-bit memory address space provided by the x86-64 architecture. Microsoft Windows XP Professional 圆4 Edition, released on April 25, 2005, is an edition of Windows XP for x86-64 personal computers.

Windows xp x64 sp2