Depending on your motives, a fun alternative to the popular Arduino for getting into microcontrollers is just ordering the naked parts and wire them yourself on a breadboard, following Sparkfun's excellent tutorials ("Beginning Embedded Electronics" on http://www.sparkfun.com/commerce/tutorials.php). They start out very basic with building a 5V circuit, connecting an AVR, programming it, adding a crystal and a RS232 level shifter to talk to your serial port, etc, all well explained for beginners. As a software person eager to learn the electronics behind it I've had a lot of fun that way. Great company!