There are many programs that will rename files quickly and easily.

MP3Tag is the most notable as you can tell it to rename files based on the MP3 title tag or to edit the tags themselves. They also have lots of documentation on how to convert between the two using the various menu options.

Total Commander is an alternative to Windows Explorer. One of the built-in functions is a multi-file rename tool, with documentation on using the multi-rename tool.

muCommander is an alternative to the Mac Finder. One of the built-in functions is a multi-file rename tool.