Seriously, give textpipe a look 
I have personally done some pretty crazy operations on hundreds of thousands of files before, so it will definitely do what you’re after.
Here is a thread on donationcoder.com discussing various search/replace tools.
http://www.donationcoder.com/Forums/bb/index.php?topic=9401
Some more links straight to programs too.
And more:
http://www.snapfiles.com/Freeware/productivity/fwwordprocessing.html
http://www.snapfiles.com/Shareware/productivity/swwordprocessing.html