Need a new mp3 player?

Okay, I need a new MP3 player. I want something that uses standard AA's or AAA's; I use Nickel Metal Hydride rechargeable batteries, so I don't like rechargeable built-in batteries. I need one with an SD expansion slot, and the player needs to be flash-drive based. I don't watch videos and play any other weird formats apart from .wma and .mp3. Most importantly, something with good sound...that's the most important to me. I don't have to have a radio, video player, sound recorder, etc. in it. Just an mp3 player only, if it involves sacrificing quality of the music in place of extra features. A decently backlit screen would be nice...but most of them have that anyway. Oh yeah...preferrably something that supports playlists and plugs in via usb cable. Those flash-drive 'plug and play' players mostly don't seem to support playlists...but rather confusing folders or a lot of them just randomly accept the music and jumble it around.