The Slim X is definately a nice player, as was pointed out though, the lcd is kinda small. If you put multiple songs by the same band on a cd it's really annoying since the the song titles aren't displayed until leaving a song selected for a few secs (for artists with longer names that it). Other than that the sound is utterly amasing for an mp3 player and once you get used to the multifunction inline remote there is no going back. The rio is a great player too but it's damn bulky and beware the lid is plastic and attached rather poorly (my friend has already broken the lid on her 250), but since it is also made by iriver for rio it should have the same great sound.
That said the rio and the slim x are increadibly good deals, but despite it's smallish lcd i wouldn't give up my slim x anyday.....Having the small footprint and inline lcd remote (read as- not having to pull out the player to read the lcd to pick a different dir or certain artist) really makes the Iriver worth the xtra cash.