Digital cameras: New person seeking help choosing a new camera. ( Kodak?)

New person seeking help choosing a new camera. ( Kodak?)

Hello, please help me choose a new camera.

I currently have a Kodak DX7440. I would like the new camera to be an upgrade to this camera. I will probably choose another Kodak as I've liked how user friendly is it, however feel welcome to suggest other brands as long as they fit the requirements I have laid out.

I am causal photographer who takes my camera hiking, outtings, normal social type pictures and uses it to photograph my aquarium fish.
Sometimes I take it kayaking in a special protective bag I have.


OK here is my list of requirements:
- Must be an upgrade/ better then the camera I already have otherwise not much point in buying a new one.
- At least 8MP.
- The same size or smaller then the current model.
- Will not cost more then $400 (this about what I spend on the DX7440 a couple of years ago) .
- I am willing to shop around and if the right model is more then $400 , I will buy it used.
- Will use the same memory sticks ( SD).
- Will use a rechargable battery.
- Will take decent pictures of aquarium fish/ has a decent macro lens?.
- Will take short movies ( Do they all do this these days?).. I think so.
-I have a mac mini computer 1.42 processor speed. It would be best if the camera would work with this.

I'm aiming to get this new camera by June if possible.
Any other suggestions appreciated such as things I haven't mentioned or other resources I should check out for my personal research.
Thanks in advance, hope to hear from some experts out there.

My personal and phone number so you experts can reach me is...HAHA gotcha, just kidding...