Change all file names in specific folder

Question

Hi,


I want to change all file names in a specific folder including sub folders files, How can i do that.


example:


I want to change all file names (Actually i have to give only one common number to all file names in one folder) in a NumberFolder1


My Folder1 structure like this:


NumberFolder1
                - Folder2
                       -abc.xls
               -folder3
                        -xyz.xls
                       -123.xls


Now, I want to add a name(Number) to all files, the result should be like this:


NumberFolder1
               - Folder2
                      -Number_abc.xls
              -folder3
                     -Number_xyz.xls
                     -Number_123.xls


Thanks


Darma