O reconhecimento de manuscrito é incorporado por padrão no Windows XP. Veja aqui como instalá-lo:
How to install and configure handwriting recognition in Windows XP
É claro que você ainda precisará de uma "ferramenta de escrita" para fazer uso dela. Dos requisitos:
- A writing tool. The minimum requirement for a writing tool is a mouse. To write with your mouse, press and hold down the primary mouse button, and then move the mouse pointer to form characters. The recommended tool is a handwriting input device, such as a pen stylus and tablet, connected to your computer through a serial port or USB port. Graphics tablets that are used with three-dimensional (3-D) drawing or computer-aided design (CAD) programs can also be used.