[14] It also introduces Kernel Patch Protection (also known as PatchGuard) to improve security by helping to eliminate rootkits.

[15] The primary benefit of moving to 64-bit is the increase in the maximum allocatable random-access memory (RAM).

Since the x86-64 architecture includes hardware-level support for 32-bit instructions, WoW64 simply switches the process between 32- and 64-bit modes.

As a result, x86-64 architecture microprocessors suffer no performance loss when executing 32-bit Windows applications.

Although 32-bit applications can be run transparently, the mixing of the two types of code within the same process is not allowed.

[30] In fact, due to the earlier release date of the 32-bit version, many of the key features introduced by Service Pack 2 for 32-bit (x86) editions of Windows XP were already present in the RTM version of its x64 counterpart.

A machine running Windows XP Professional x64 Edition cannot be directly upgraded to Windows Vista because the 64-bit Vista DVD mistakenly recognizes XP x64 as a 32-bit system.

Despite this, there is a workaround available via third-party tools that makes upgrading from XP x64 to Windows Vista possible.

[32] Extended support lasted until April 8, 2014, in line with all other Windows XP editions.

[38] In 2020, Microsoft announced that it would disable the Windows Update service for SHA-1 endpoints.