I am working with a very big project (a solution that contains 16 projects and each project contains about 100 files).
It is written in C++/C# with Visual Studio 2005.
In the Solution Explorer, right click and on a Reference and click on the menu item Find Dependent Code.
If it can't find any dependent code then you can remove this reference from the project. (The Remove operation is also under the right-click menu.)
EDIT: For a large project, the Find Dependent Code operation will take a long time. So since you have 2000 resources and most likely value your time this probably is not a viable option....