The NUnit Converter was written for developers with an existing C# or VB.NET NUnit code base who were interested in evaluating the unit testing tools in Visual Studio Team System. In the Readme there is a detailed description of the differences between the tools and the way that the converter will modify your source code to make it compatible with VSTS. The tool does its best effort to convert the code but there are a small number of instances where the conversion is not possible.
This content was previously hosted on GotDotNet at http://workspaces.gotdotnet.com/nunitaddons.
The tool has been tested against NUnit 2.2.4, Visual Studio 2005, and Guidance Automation Toolkit June 2006 CTP.
Note: Please be advised that this tool is provided as is and there will be no further updates.