Q:

How do I know which files I actually changed since my last TFS checkout?

I've checked out a bunch of files from TFS in VS2010 and made changes to several of them.  How can I see which files I actually made changes to?

A:

Use the TFS power tools. Open a visual studio command prompt, navigate to your workspace and then type 
tfpt uu /noget /recursive
This will undo any pending changes on files that haven't been modified

