If you decide to go the DSLR route you need to consider more variables than you do with a point and shoot (P&S) camera.
The order of importance, in regard to picture quality, with a DSLR is:
Photographer skill, lens quality, camera body.
Every DSLR body on the market today will take excellent pictures. Your lens choices are far more important than which body you buy.
You also have to be comfortable with how the camera feels. If you're not comfortable with your camera you won't be out shooting with it. Go to a local camera store (avoid places like Ritz, Best Buy, etc.... if at all possible), play with several different camera bodies and see what feels the best in your hand. Buy the one that feels best.
/ personal rant /
If you go to a local store with subject expertise (again, not a Ritz, Best Buy, Wolf Camera, etc) and take advantage of the knowledgeable folks buy your camera there. You might pay a little bit more but they deserve to be compensated for their assistance. In the long run building a relationship with a local store can be very helpful as a good camera is a long term investment. I have no problem buying online to save money; I just don't do it if I've involved the local store in the sales process.
/ end rant /
Buying a DSLR is more than buying a camera, it's buying into a system. That being said Canon and Nikon currently have most of the market. Choosing one of those gives you more choices for expansion down the road. The new Sony looks good as well and it's compatible with Konica/Minolta lenses.
If saving money, by buying used gear, allows you to spend more money on lenses you should go that route. A good lens on a used body will take better pictures than a cheap lens on a brand new body.
Cheers