When using the Visual Studio integration for TFS 2008, you will notice that the latest version will not be retrieved when you start making changes to a file.
There is an option that you need to have an option. To get to this option perform the following steps:
Launch Visual Studio 2008
Expand the Source Control section
Click on Visual Studio Team Foundation Server
Ensure that the Get Latest version of item on check out is checked.
Now when you check out a file if you don’t have the latest version, it will prompt that you don’t and fetch it for you.