Using the command promt, navigate to C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE
Now, using the tf.exe tool
tf workspaces /updateComputerName:MyOldComputerName /s:http://TFServer:8080
tf workspaces /updateComputerName:MyOldComputerName /s:http://TFServer:8080
<setting name="Counters.Enabled" value="true" />