VS.NET comes in many editions with some limitations.
For example: VS.NET Express does not allow you to have any plugins (or used to, never checked anymore) which means you can't run your NUnit from there and expect code-coverage instantly show up once you ran them.
Their NuGet solution somehow seems limited compare to Maven eclipse plugin where it can download the JAR, JavaDoc, and Source if required whenever someone needs to navigate the source code of 3rd-party lib.