You can't have Googled for suitable software before asking the question, 'coz there are loads of programs available!? I'll leave you to wade through all the hits yourself though, to find out which ones - if any, are free But to show I do have a heart... here's Mobile Ringtone Converter to get you started. It's not FREE, but @ just $14.95 (around £8), it's inexpensive
I had a search on Softpedia and found this: http://www.softpedia.com/get/Multim...s/MP3-Converter-from-rm-wmv-asf-avi-mpg.shtml I'm not sure as the features are limited as its a trial version but, most definetly are, hope it helps.