Arduino is an open-source electronics prototyping platform based on easy to use hardware and software.
The on-board microcontroller can be programmed using the Arduino Programming Language.
The environment makes it easy to write code and upload it to the i/o board and runs on Windows, MacOS X and Linux.
A Getting Started guide for Windows is available at
http://arduino.cc/en/Guide/Windows
But first you need to buy one and unwrap it
To reveal its full glory