After having trouble with a Cowon MP3 player (broken hardware) and a Sony MP3 player (breathtakingly bad software - to the point where it's nearly useless and I'm tempted to smash it into fine dust with very heavy sledgehammer), I'm quite pleased with my new Creative MP3 player, which seems to have both good sound and sound design (double meaning semi-intended).
Some more details: The really bad thing about the Sony is that the term "MP3 player" is actually a misnomer for their horribly designed machine - it does not in fact play MP3 files at all, but rather has some very badly designed software that converts them into a native Sony format that sounds muddy and is hard to work with.
Well - enough on that - but if you're in the market for an MP3 player I really do recommend that you avoid Sony and buy Creative instead. Creative is the same company that's been making sound boards for computers all this time after all - they should know something about making electronic sound parts!
Lyle (Hiroshi) Saxon