I own a 300SE and aside from the fact that it has updated firmware and more memory it is exactly the same.  I was worried about things that I had read stating that the case was shoddy, the volume level was insufficient  and the memory didn't hold enough.  I just wanted to say that all of this  IS NOT true.  It seems really solid to me, not that I'd ever drop the thing  or be rough with it, but it does just fine while jogging or riding a  bike...as for the volume level comments perhaps people are just listening  to songs encoded at a low base level because I listen to mine on level 5 of  20 and it's fine for most songs unless I'm in a REALLY noisy  environment...lastly I listen to all of my songs at 128k. and I can fit an  acceptable amount of music on my 64megs--no it isn't as much as a CD but  with 2 32meg smartmedia cards on the way that should be more than enough to  get me through all but the longest of plane flights.  With the portability  of the transfer cable and software I can just burn all of my mp3s to a Cd  or 2, throw it in my luggage and change the songs out from wherever I  happen to be...much more efficient than lugging around all of my CDR mixes  and other CDs.  True the parallel transfer is much slower than the USB that  the 500 offers, but do I really want to use USB when places that I travel  might not offer USB support?  Also the backlight of the new 500s are  supposed to drain the battery power and I don't find the lack of a  backlight to be as big of a problem as I thought it would be, however.  I  would definately recommend purchasing the rio remote as it super easy to  use and extends the headphone's cord length by a good 2 feet.  See ya!