Converting .RAR files to iTunes/iPod-compatible format!

Hello.

I recently downloaded a music file from Megaupload, and it was saved as a .RAR file in my iTunes Music folder (I can't save it as anything else, I don't think). When I go to iTunes and click 'Add file to library', it does nothing, as I realized that .RAR files are not compatible with iTunes. Is there any way I can convert this file into the appropriate format? Thanks in advance