How many different versions of Windows XP are there?

Windows XP Starter Edition
This edition is aimed for first-time desktop PC users in developing countries. This edition can only run three applications at once.

Windows XP Home Edition
A version of Windows XP for home users. This edition replaced Windows 9x/ME

Windows XP Home Edition N
This is a special edition of Windows XP Home Edition for the european market
without media player

Windows XP Professional
A version of Windows XP for both businesses and home users. This edition replaced Windows 2000 Professional

Windows XP Professional N
This is a special edition of Windows XP Professional for the european market without media player

Windows XP Media Center Edition
A Windows XP version for Media Center PCs with an easy to use interface and remote control support

Windows XP Tablet PC Edition
This is a Windows XP version for Tablet PCs with pen and speech capabilities

Windows XP Professional x86 Edition
This edition is for AMD64/EMT64 64-bit processors