I blog about debugging, development using .net, C#, SQL, and other Microsoft technologies.
Disclaimer: All posts are provided "AS IS" with no warranties, confering no rights, and expressing only my personal opinion, not Microsoft's.
When you check-in, TFS will warn you that you have conflicts and the check-in fails. However, you may want to preview the conflicts without proceeding with the check-in. In this case you can run tf checkin /validate which lets you test checking in without actually doing it. You can also use it to evaluate check-in policies and check check-in notes.