Here is a list of resources that we found useful:

• OpenCV - open source computer vision software library from Intel - the standard. http://www.intel.com/technology/computing/opencv/
• Johnny Lee's website - http://www.cs.cmu.edu/~johnny/projects/wii/
• Microsoft C# Express - free tools to build the software. http://www.microsoft.com/express/vcsharp/
• OpenCVDotNet - C# wrapper for OpenCV. http://code.google.com/p/opencvdotnet/

There's plenty more out there, but these are the main ones we used.