To customize windows user need to edit or replace a system file . Which requires to take ownership of that file , stop the process using it , so it can be replaced .
We already posted about add Take Ownership option in right click menu here
But Windows Se7en File Replacer is a nice little 3rd party application with which user can easily change Windows 7 System files .
Windows Se7en File Replacer has both Automatic & manual mode of file replacement .
Also the old files can be easily restored with it .