release date:
I e-mailed Creative about this, and they said it should be out some time this week. I'm not sure if that's right, but look for it before the holiday season.
difference of players:
flash players - usually have less capacity and run on AA/AAA batteries or rechargeable. Have no moving parts, making them ideal for jogging and working out. Usually smaller in size.
Hard Drive - as it says, these players contain a hard drive, much like the one on computers. Just smaller. These are for people who are maybe DJ's, or make long commutes, and therefore want all or most of their music with them. Almost always have a built-in rechargeable battery, usually not replaceable. Has a moving hard drive, so should be handled with care and should not be bumped or jolted.
hope this helps.
When does it come out? Also what's the difference between a hard drive player and a flash player?

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