Personally i would use Blender (free open source software
http://www.blender.org)
it does 3D modeling and inverse kinematics (IK).
Real-time control is handled by the Blender Game Engine. Although i use blender for 3d modelling im not familiar to using this in Blender myself, i have seen loads of examples, so finding more info will be quite easy.
A Python 3.2 (
http://www.python.org) script (Blender 2.59 comes prebuilt with Python 3.2) runs inside of Blender and continually sends joint angles to a socket port.
A Processing (also free and open source software
http://www.processing.org) program runs as a socket server and recieves a string of angles from Python.
Arduino Uno (open source microprocessor board
http://www.arduino.org) recieving commands from the processing sketch through a USB/Serial Port connection.
a similar project you might find interesting:
http://justindailey.blogspot.com/2011/0 ... c-arm.html