I found a great free tool and thought I'd share it here. It's called "Bulk Rename Utility" and can be downloaded from http://www.bulkrenameutility.co.uk/Command.php.
This utility is GUI based, but the link above is the command-line version. I also highly recommend you download the manual to see all the features it has.
When you download the command line version, it is called BRC64.exe ( and they have a 32bit version). I just dropped this into the Windows system directory so its available from the command line no matter what directory I am in.
If you type: BRC64.exe /? , you will get all the command line options.
The main concept is if you run the command with the options, it WILL NOT MODIFY the filenames until you add the /EXECUTE option. So, you can play around with all the options and it will show you what WOULD HAPPEN, then you add /EXECUTE to make it happen.
-- This will insert ACME in front of all .X01 files, then remove the .X01 and add .txt as the suffix
brc64.exe /PATTERN:*.X01 /INSERT:ACME-:0 /REMOVEEXT /SUFFIX:.txt /EXECUTE
-- This will replace 2012 with 2011 in all .txt file and change .txt to .asc
brc64.exe /PATTERN:*.txt /REPLACECI:2012:2011 /REMOVEEXT /SUFFIX:.asc /EXECUTE
There are a lot more features, but you get the idea. Just remember, it WILL NOT perform the rename until you add the /EXECUTE, so you can experiment all day.