A. I bought one of these and wasted ages trying to get it to work until I found some great instructions at http://sites.netscape.net/richij/rio500-win2000.html. The instructions show you how to use a special USB driver and a special version of the Audio software.
An alternative method which I've since found is to use the same USB driver (http://www.ntfaq.com/download/riousb.zip) and extract to a directory. Attach the RIO500 via USB and power it on. When it asks for a driver specify the location you extracted the ZIP to.
To actually copy the MP3 files to the RIO500 you can use RealJukeBox (http://www.realjukebox.com) which has a RIO500 add-on which is great. If you have trouble installing the add-on (maybe due to a firewall) just extract rio500.dll from http://www.ntfaq.com/download/rio500.zip to the Plug-in's directory of Real Jukebox (C:\Program Files\Real\RealJukebox\plugins), restart the software and you should be able to add it as a device (Options - Preferences - Portable players/storage - Add) and copy away. Its very cool :-)