How do I coverte rar files to mp3?

Which service offers rar music files?

RAR isn't a music format. It's a compressed file with files INSIDE it, like ZIP files. You need to download a RAR tool to open the compressed file.

WINZIP does it, opens both ZIP files and RAR files. Or, Win-RAR does the same thing.

WinRAR download and support (http://www.google.com/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Fwww.win-rar.com%2F&ei=XniHSMz4BoSI8gS5oo3iBQ&usg=AFQjCNH055DHYAjYEJ1Gw65UxXEx1EqSOQ&sig2=r85Sziwo_MHlO58cSJpinQ)
WinZip® - Select a Product Download (http://www.winzip.com/prod_down.htm)

WinZip isn't free, but many home users never "buy" a license since it works anyway. Your call.