A "System.NotImplementedException was unhandled error" in Microsoft Visual C# 2008 Express Edition happened for the sample apps that came with the Microsoft Surface SDK and Surface Simulator. This was a huge problem until I found the Solution to this problem. It is simple. First, you have to show advanced build configurations by going to "Tool -> Options -> Projects and Solutions -> General", clicking the "Show all settings" and checking the "show advanced build configurations". This will make it so the "Build -> Configuration Manager" will show in the main window drop-down menus. Go there and "Add new..." with x86 processor run the apps without these problems.
MS Surface in the Store