I\'m looking to introduce a unit testing framework into the mix at my job. We\'re using Visual Studio 2005 (though we may be moving to 2008 within the next six months) and
MbUnit is worth a look. It has a set of features comparable to NUnit. It has its own GUI, or can be integrated into Visual Studio if you have ReSharper. I would also recommend Rhino Mocks if you are doing any sort of TDD.