Canon, Nikon, Sony...etc...each have good entry level DSLRs. As stated you have to ask yourself what you want to do with it. Are you looking into an eventual career? Do you just want a good camera for a serious hobby?
Either way I feel it is best to not go crazy right out of the box until you are sure you will get enough out of it to invest some serious cash.
The canon XS, XT or XTI are good beginners that won't break you. Nikon has the D40, and Sony's Alpha 200, are a step up and still a reasonable price.
These cameras all have enough features that you can learn the basics of cameras and experiment with the fundementals of photography.
I would also suggest getting at least one good lens. A camera is only as good as the lens in front of it. (Some may argue this, but I believe it.)
Read about photography basics...exposure, shutter speed, aperture, ISO...etc.
Bryan Peterson has two great books that most people will agree are gotta haves for new photographers..."Understanding Exposure" and his follow up "Understanding Shutter Speed"
Of course there are many others out there that have good information as well.
Once you get this basic knowledge down you will be able to understand more about what you are doing with the features of your new camera.
Good luck with your decsision, and let us see what you come up with.