For some reason I find myself having to rename/retag large numbers of files a lot. I always used to use DOS command lines but I found a nice shareware utility that does everything I need.
Its called FlashRenamer.
It has dozens of options, can modify timestamps, alter case, change attributes etc. And it is very fast. I lowercased over 3000 files in just a few seconds.
Always nice to find a useful utility!