As regular readers will remember, my beloved mp3 player died a few weeks ago. One of the reasons for my purchase of the Sony Reader was its ability to play mp3s. The internal memory of the PRS-505 is a tiny 256 megs, but there are two memory card slots-- one for a Sony Memory Stick and one for an SD card.
Books take up very little memory. I now have 320 books on my reader and have filled up only a teeny pie slice of one data card. Mp3s on the other hand use a bit o' memory, so I bought a 2 gig Sony Memory Stick Pro Duo, and a 4 gig SDHC card. So far I have only a dozen or so songs loaded but I have room for almost as many as I had on my GoGear. Note: The Sony Reader will play mp3s, but not wma files.
I read on my Sony Reader all the time, but I've only plugged in earbuds once or twice. The sound is top notch, but I'm so into my reading that I forget all about the music.
Addition: I plugged my Reader into my speaker system to listen to music last night and it stopped twice-- once at the end of a song and once in the middle. I've got to check it out and see if there is something wrong with those two particular mp3s.