Ant Renamer
Free program that eases the renaming of lots of files and folders
..., Regular expressions.
Available in several languages.
Unicode file names are supported, so it is possible to rename without problems files that have names containing characters from Japanese, Chinese, Arab, etc. This may seem common nowadays, but back then when it was added (2003) it was a big plus.
Tested successfully under various Windows versions, from 98 (possibly with a few updated system files) and NT4 (SP4 required) up to current ones (Windows 10/11 included).