Assert.Throws provides the Assert.Throws method for testing exceptions, instead of the ExpectedException attribute. In his original announcement, James Newkirk explains why this is a much better approach, and I can only agree.

However, those of us that for one reason or another use MSTest are currently stuck with the ExpectedException attribute, but I've entered a suggestion on Connect that we get a similar method in MSTest. If you would also like to have Assert.Throws in MSTest, go to the suggestion and vote for it!