NUnit vs. Visual Studio 2008's test projects for unit testing [closed]

I am going to be starting up a new project at work and want to get into unit testing. We will be using Visual Studio 2008, C#, and the ASP.NET MVC stuff. I am looking at using either NUnit or the built-in test projects that Visual Studio 2008 has, but I am open to researching other suggestions. Is one system better than the other or perhaps easier to use/understand than the other?

I am looking to get this project set up as kind of the "best practice" for our development efforts going forward.

Daok named all the pro's of Visual Studio 2008 test projects. Here are the pro's of NUnit.

• NUnit has a mocking framework.
• NUnit can be run outside of the IDE. This can be useful if you want to run tests on a non-Microsoft build server, like CruiseControl.NET.
• NUnit has more versions coming out than visual studio. You don't have to wait years for a new version. And you don't have to install a new version of the IDE to get new features.
• There are extensions being developed for NUnit, like row-tests, etc.
• Visual Studio tests take a long time to start up for some reason. This is better in Visual Studio 2008, but it is still too slow for my taste. Quickly running a test to see if you didn't break something can take too long. NUnit with something like Testdriven.Net to run tests from the IDE is actually much faster. Especially when running single tests. According to Kjetil Klaussen, this is caused by the Visual Studio testrunner. Running MSTest tests in TestDriven.Net makes MSTest performance comparable to NUnit.

The unit-testing framework doesn't actually matter much, because you can convert test classes with separate project files and conditional compilation (like this, Visual Studio → NUnit):

 #if !NUNIT
  using Microsoft.VisualStudio.TestTools.UnitTesting;
 #else
  using NUnit.Framework;
  using TestClass = NUnit.Framework.TestFixtureAttribute;
  using TestMethod = NUnit.Framework.TestAttribute;
  using TestInitialize = NUnit.Framework.SetUpAttribute;
  using TestCleanup = NUnit.Framework.TearDownAttribute;
  using TestContext = System.String;
  using DeploymentItem = NUnit.Framework.DescriptionAttribute;
 #endif

The TestDriven.Net plugin is nice and not very expensive... With only plain Visual Studio 2008 you have to find the test from your test class or test list. With TestDriven.Net you can run your test directly from the class that you are testing. After all, unit tests should be easy to maintain and near the developer.