Lots of programs can download RM streams including RM Recorder, Mass Downloader, HiDownload, NetTransport, r7c (real7ime converter), Streambox VCR, VLC.

r7c can convert RM files to MP3 or WAV, however I dunno how to schedule it.

You may also download and convert RM files to other formats using VLC player. It has a command line interface that can be used when scheduling.

You may also download a stream with any stream recorder supporting Real Medis streams and convert it using video conversion software.