What version of TFS do you have? The full edition? Workgroup edition? or maybe Trial edition?
To answer this question, open your registry (Start-->Run-->regedit.exe) and navigate to:
Note: If you have TFS 2005, replace the 9.0 with 8.0
You will find in this key a value named Edition_CT. This value is a string that indicates the edition you have. (This text equivalent to the encrypted key of the Edition value)
- Full (The standard edition)