"Richard the picture man" gave you some of the best, most succinct advice I've seen in a while. To quote:
"So, what is the point of my rant? Well, save yourself loads of heartache and frustration, just do the following sequence in your buying procedure.
1. Decide on your budget and stick to it.
2. Go to as many places as possible and handle every DSLR in your price range.
3. Choose the one that is most comfortable in your hands.
4. Buy it.
5. Start the learning process by taking lots of pictures
6. If and when you get stuck ask for help here.
7. Have lots of fun."
I tend to recommend Canon or Nikon for most people, mostly because they offer the most expansive systems , and eventually just about every DSLR owner I know ends up buying more 'stuff'. BUT: if you look at Olympus, Pentax and Sony and are satisfied with their range of lenses, remote releases, flash and so on, then by all means add them to your consideration. All will produce excellent images in skilled hands .
Canon and Nikon both have seriously great lenses...but are you going to be willing/able to afford to buy them? Or are you going to stick with their consumer grades of lenses (which are also very good)?
One of the most important things about a DSLR is ergonomics (they all have so many features that you'll be inundated for a while). Richard's advice to handle cams is right on: you need to see how a cam feels in your hands and thumb through the menus. Most people I know prefer Canon or Nikon based only on this, as lens selections from both are great. I'm a Canon shooter, but if I was starting over today, I'd probably go for Nikon. And that might change back next year. Canon and Nikon are extremely competitive with each other and their #1/#2 positions change regularly.
You also need to think carefully about what you're going to shoot. If you shoot things like concerts, indoors under available light, and so on, you'll want to look at reviews and check out high-ISO performance, perhaps.
One thing: don't forget to budget for a good tripod. You may not feel an immediate need for one, but if you get serious about photography, you'll almost certainly need one eventually. A good tripod can cost as much as a low-end DSLR, so just be prepared.
Abbott