honestly, if you have to ask, I'll assume your experience with cameras is limited. first, decide if you want a dSLR. P&S will cover most of what the average person wants in a much easier format.
if you want to shoot for art/portrait/sport... go dSLR and figure out what kind of photography you might be interested in.
the newest digital rebel is insanely cheap and matches the D300 on most features (please don't flame). that or the D300 would be great starting points from which to acquire new lenses and learn more.
I wouldn't start with high level cameras. by the time you figure out how to use it effectively, it will be somewhat obsolete. you'll pay for bleeding edge, but not be able to use it.
better to get something decent and play with it for a year or two, from then, with experience, you'll have a MUCH better idea of your needs and wants.
We shoot D300s and love them. Have no reservations about recommending them. That said, if Canon's 5D replacement was here tomorrow, we might pick up 2 of those as well. I prefer Nikon, but in the end, they're just tools. Whatever gets the job done for YOU. (though I will admit that the 5D is a better tool for me in portrait work)