I've updated my Visual C# .NET application for accessing generic HID-class USB devices:
Generic HID CS 6.0
http://janaxelson.com/hidpage.htm#MyExampleCode This version uses .NET 4.5's new ReadAsync and WriteAsync methods for Filestreams. Unfortunately, the .NET 4.5 redistributable (required to run the application) is compatible only with Windows Vista and later. So this version will not run on Windows XP.