how can I easily change a lot of file names?

I'd like to do somethine like search and replace...

[Craig_F]

I have 1000's of files that I need to rename, is there an easy way to do this?

[AsleepATheWheel]

I use a program called Reanmer, it's a great program for doing this type of thing. You can get it here:
h*tp://graphicssoft.about.com/library/daily/bldd030200.htm

Paul

[Longhaired Genius]

Another one for Windows: h*tp://www.1-4a.com/rename/

It can seem a bit odd at first but is very versatile once you get used to it.