I also have the original Diamond Rio player, and like der.hans
mentioned the Linux software lets you do more with it than the
program supplied by Diamond (i.e., retrieve files from the Rio
as well as store files on that device).  I have not tried any
of the newer units, or any that are USB-based.  The original
Rio worked through a PC's parallel port.

Then again, another approach to having a portable MP3 player
might be to get one of those portable CD players with MP3
capabilities.  The low-end units (roughly < $100) seem to be
set to only play 128kbps stereo (and sometimes 64kbps mono)
MP3s, but the more expensive ones often handle other encoding
rates.  You need a CD burner to make your MP3 discs and then
get a player, but if you already have a CD burner this might
be a cheaper alternative than players like the Rio.  Going
with an MP3-capable CD player lets you bypass the worries of
locating Linux software for the player you want to buy/use,
blank CDs are cheap, and hold a lot.  Having 9 to 10 hours of
MP3 music on a CD beats only 30 minutes or so on the Rio I
have (using 128kbps encoding) - perfect for most long flights.
If I need more I can always make a second CD so I don't have
to listen to the same track twice on longer overseas flights.

Good luck!


Patrick

-- 
Patrick STODDARD                E-mail: wd9ewk at amsat dot org
Glendale, Arizona, USA          ICBM:   33.5 N 112.2 W