How do I rename audio file extensions?

[Spoon]

For example you might want to rename .rmj files to .rm so dMC can convert them. Use A.F.5 to rename these files:

http://www.fauland.com/af5.htm

"basically install and run af5, run a windows search for all files with .rmj extention, drag them into the af5 window and use the replace function to change the extensions to .ra -- then the converter will recognise them, and you're in business"