I was in your situation a number of years ago: I thought I had some eye for photography, and wanted something to replace my trusty Canon point-and-shoot. This was before digital was affordable to mortals ('99). My budget was tighter than yours, but I did quite a bit of research. I did pretty much what Michael did in his watch essay, I listed my requirements:
- Good selection of lenses to grow with me and the system
- Ability to go beyond 30 second exposures since was planning to shoot low-light cityscapes - which has become one of my favorite subjects
- Fully manual mode for the same reason
- AE bracketing since I didn't know how to expose properly at the time, and was planning to shoot slide film - for best quality - which is not very forgiving to exposure mistakes. (Yeah, yeah, I know I should learn to shoot before buying a camera and all that.)
In the end, it was the things that I _didn't_ need that narrowed the selection to two cameras (in addition to budget):
- I have no need for really fast shutter speeds since I'm not interested in sports photography
- No need for fancy autofocus tech for the same reason
I ended up getting the Canon EOS 50E (Elan II-E), which was a prosumer film camera. There were nicer and more expensive offerings, but they had features that I didn't need. Therefore I wouldn't have bought them even if I could afford.
When I moved to digital I was faced with the same decision. I went with 30D, which is the prosumer Canon digital. I am extremely happy with it. I have no plans to upgrade it to 40D or any of the new offerings, as I feel that my photography is better served by investing in good glass. The glass will last for years longer than a digital back.
So, I'd take a long, hard look at how I shoot, what I want to shoot, and base my decision on that. Don't get too caught up with your budget, as it's big enough to get you very nice serious amateur gear. But remember that you will invest quite a bit more than just the lens and back: bag, memory cards, tripod, lens hood, filters, software, printer, paper, inks, and some LL tutorials