If you want to "get into it" and see yourself eventually taking it seriously as a hobby, then it's not a bad idea to stick with Canon or Nikon. The other brands can certainly make good images, but the big two just have so many more options when it comes to third-party support, used equipment, and all the other benefits that come with a very large user base. I'm personally a Canon guy but Nikon has excellent offerings as well.
As for starter equipment, I would probably go with a lightly used Rebel. A T2i or T3i is a great choice, with the T3i being a little newer and having a few additional features. They have the same sensor as the 60D and 7D, which means competent low-light performance, and overall very good image quality for a starter camera. If those are out of your price range or you won't buy used, the T3 (not T3i) is an okay choice for a super low price - though the T3 is certainly much more "entry level" when it comes to size and features; also, I don't know much about the sensor in the T3, other than it's different and a little smaller than the other Rebels.
Camera bodies depreciate quickly, whereas good lenses hold their value for much longer. Therefore, definitely don't rule out a gently used body that someone else has outgrown; let someone else take that depreciation hit for you, and spend the savings on the other stuff you'll need, like lenses, a memory card, flash, bag, tripod, remote shutter release, the list is just about endless. About 1/3 of my equipment was bought used, including my two favorite lenses.
Also, if you want to get the most out of your camera, invest in the book Understanding Exposure
by Bryan Peterson. Modern DSLRs are pretty smart, but when left on the fully automatic modes, they will do a good job of making a perfectly average picture in every possible situation. Once you understand the exposure triangle (shutter speed, aperture, and ISO) you can move away from the automatic modes, tell the camera what you want it to do, and take your photographs from "average" to "pretty good" and then to "fantastic."
Also, the forums on http://photography-on-the.net
are a fantastic resource for novices and pros alike. That particular forum leans more toward Canon, but the fundamentals of photography are the same regardless of the brand of the camera.