The 2005 edition is available as a service pack upgrade, or as a new OEM version.
Requirements to install Tablet PC Edition include a tablet digitizer or touchscreen device, and hardware control buttons including a Ctrl-Alt-Delete shortcut button, scrolling buttons, and at least one user-configurable application button. Tablet PC Edition is a superset of Windows XP Professional, the difference being tablet functionality, including alternate text input (Tablet PC Input Panel) and basic drivers for support of tablet PC specific hardware. Except for MSDN and Volume License subscribers, Windows XP Tablet Edition could not be purchased separately. Windows XP Tablet PC Edition is compatible with a pen-sensitive screen, supporting handwritten notes and portrait-oriented screens. This edition is intended for specially designed notebook/laptop computers called tablet PCs.
