What are the different versions of Windows XP?
In 2002, a third edition, called Windows XP Media Center Edition was introduced and was updated every year until 2006 to incorporate new digital media, broadcast television and Media Center Extender capabilities. Unlike the Home and Professional edition, it was not available for retail purchase, and was typically either sold through OEM channels, or was pre-installed on computers that were typically marketed as "media center PCs".
2 diverse 64-bit versions were available, one designed specifically for Itanium-based workstations, which was introduced in 2001 around the same time as the Home and Professional edition, but was discontinued a few years later when vendors of Itanium hardware stopped selling workstation-class machines due to low sales. The second one called Windows XP Professional x64 Edition, supports the x86-64 extension of the Intel IA-32 architecture. x86-64 is implemented by AMD as "AMD64", found in AMD's Opteron and Athlon 64 chips, and implemented by Intel as "Intel 64", found in Intel's Pentium 4 and later chips.
Windows XP Tablet PC Edition was created for a class of specially-designed notebook/laptop computers called tablet PCs. It is well-suited with a pen-sensitive screen, supporting handwritten notes and portrait-oriented screens.