Personally if you want to really get serious into photography, I think you should do more than deciding on which particular camera body to get. Rather, go readup more on the strength and weakness of each individual system before you decide on which SYSTEM to go into.
Camera body is always changing even within a brand whilst the rest of the accessories like Lens, Flash, etc will stay with you much longer. And you probably have more lens than DSLR body after a few years. Also, take a look at the B&S thread and see for yourself which brand has more used accessories on trade. This might save you some $$$ whether you are buying or selling.
Lastly, when you have decided on a brand, you might consider a used DSLR with a good (eg 50mm 1.8) lens to start with and build your interest from there. A lot of guys (myself included) rushed into getting an around lens covering a wide range (especially tele) but due to budget, sacrifice on image quality (quite a common "mistake" for newbie in my opnion)
just my 2 cents worth...