All the mention camera would serve your need. I would add the olympus e520 to the list as it is at a great price for the kit. If go with any of the olympus, they uses compact flash card and xd card, but I would go with the compact flash card.
As mention the D3000 will not afford as much growth if you find that you want to go further with dslr. Your are also limited to AF-s and AF-i series lenses from nikon, or 3rd party lenses to support the d3000. It is the same issue with the D5000. That said, they have some very good af-s af-i lenses out there.