I have made this simple script to help you convert your rm, real audio file, to mp3. All you have to do is download it, extract it and make sure the folder containing all the files you want to convert is the top one in Finder. It will rename the files, convert them, and then rename them back. It should be able to handle all the files in the top folder.
-Create a folder in Finder and drag all your .rm files to it.
-Run the script and wait.
-Thats it.
Note: This script assumes that you have installed ffmpegX and Real player as per the guide provided earlier!
You can download the script HERE.

Update: I have updated the script to handle errors encountered during conversion.