Creating a Drag-and-Drop Upload Web Part for SharePoint Foundation 2010

Today I was working on a web part for SharePoint that would allow the user to either select files using an OpenFileDialog or via Silverlight 4’s drag-and-drop support. I came across a pretty serious issue once I completed my XAP file and uploaded it to my library. Drag-and-drop support was not available in SharePoint! When I would drag a file to the surface of the Silverlight web part and drop it, the browser would try to open the file. There is a pretty easy fix for this but I had to search all over the Interwebs to find the complete solution. Here is what you can do as well as an example of the code.