If you're looking at dslr you should be looking at:
Canon 5D, 20D, 350 XT
Nikon 200, D70
Those are probably the top five contenders.
Have a look around the board for some more information and feedback on these and dslr in general.
I still firmly believe that dslr is overkill for the vast majority of divers. A nice compact with manual shutter and aperture control will serve very well. Check out some that allow you to add wet mate macros and WA lenses and you've got a small, easy to use, quick(er) learning curve set up. Add an external strobe to open up the possibilities.
DSLR is nice, but it isn't the right choice for everyone!