Are there alternatives to the Rio software?

Try here:
http://www.mock.com/receiver

and here:
http://jreceiver.sourceforge.net

and here:
http://sourceforge.net/projects/das

and here:
http://www.reza.net/rio/rrr.html (This one includes an alternate version of the Rio Receiver player code as well.)

and here:
http://fvgestel.dyndns.org/receiver/ldaprec/ldapreceiver.htm

and here:
http://triot.sourceforge.net (alternate version of the Rio Receiver player code.)

and here:
http://homepage.mac.com/pauljlucas/software/yarrs/

Also:


http://www.xplhal.com/xplmedianet.htm a Windows XP service based multi-platofrm media server.

Also:
http://www.jonq.com/jq/projects/ampachereceiver/