If you download the MS LOC counter tool (available at http://technet.microsoft.com/en-us/library/bb897860.aspx) and then install the add-in version, you might be left wondering about how to start using the tool (at least I was!)
Before installing the MS LOC tool make sure that you have VS 2005 and Team Explorer installed on your machine. (Not sure if MS-LOC works without Team Explorer).
To start using the tool first go to View -> Other Windows -> LOC Counter Explorer.
This will bring up the LOC Counter Explorer tool.
Next you need to create a counter task and then run it.
The MS-LOC tool allows you to count code that might be stored in Visual Studio Team System or Visual Source Safe repository or even items that are stored on your file system (choice is mutually exclusive though).
For more information: