Good is ease of use and whether the mp3 player has good sound. Both the iPods and the Creative players are well known, and are fine choices. So would the Dell DJ be a fine choice. A company called iRiver also makes a good one for a lesser price.
But, and here is the thing, not all devices are compatible with all music download services. But, on the plus side, most services are just fine... stick with the well known sites and you will be "safe".
As far as how many songs each mp3 player will hold? Well, ya gotta just read the box. My opinion is that you need at LEAST 1 Gigabyte of storage, but that is just me. They have them up to 40 gigs.
I have the iPod and the iShuffle, which are both Apple products. While more expensive than others, Apple makes a GREAT product, and their iTunes software is AWESOME!
So, best advice? If you don't know enough, stick with a major player... Apple, Creative, Dell, and yes, even iRiver ( while not well known, they do get great reviews ).
BTW.... you never linked what "this" Disney mp3 player actually is. But my guess would be that it isn't made by a major player in the mp3 player market.
Good luck.
