Any of the Canon or Nikon SLRs released in the past few years are very good cameras. If you're interested in Canon, I'd play around with the D50 as well. I know it's a more expensive camera, but if you like the feel of it better than the T1i, you could buy a used 40D or even 30D for much cheaper. Both are very similar cameras. They don't have video, however, if that's important to you. I just find that the D40, D50, etc. are much easier to use than the Rebel series. The thumbwheel in back is great for either changing aperture if you're shooting in manual mode or dialing in Exposure Compensation (I know that word's probably foreign to you, but it can be a very helpful tool for getting correct exposures). The little hat controller (I don't think that's what it's actually called) is also very nice for selecting autofocus points on the fly. Either camera is very good to learn the basics of photography, though.
But even though I'm a Canon guy, I'd remiss if I didn't advise you to also try out the Nikons. They're excellent cameras with some first class lenses. Canon does some things a little better than Nikon, and Nikon does some things a little better than Canon, but for the most part, it's a personal preference. As was alluded to, however, if you get serious about photography, you'll end up spending far more on lenses than on the camera body, and the lense mounts for each camera are different. Sony cameras also seem to be gaining some popularity, and I hear Sigma is starting to make digital SLRs, so definitely don't limit your options.