Re: advice on this camera
The T1i is a fine camera, as are all of the DLSR's currently being offered from all of the major companies.
If you're looking for a long term investment, I would suggest taking a good look at what type of photography you want to do. Then once you figure that out, take a look at what lenses you are going to want in the future. Keep in mind that you are buying into a complete system, not just a camera.
Re: advice on this camera
Mike is correct, but I would like to suggest that you start with a used 35 mm "FILM" SLR camera, they are reasonably cheap, That way you will learn more about the craft. The basic photography classes at Pensacola Junior College requires their students to learn on a MANUAL 35mm camera, before transitioning to a DSLR. If you start with almost any system other than the old Canon FD mount most of your lenses will work on a Digital of the same brand. If you decide to not continue with film you should be able to sell your basic system to one of the next batch of students.
Re: advice on this camera
For a long term investment you'd be better off looking into the Canon 40D or 50D, they offer more solid build, and more on-the-fly usability that does not inhibit your field shooting experience, the rebel will have more functions and interactivity buried in menu. For a hobbyist investment the rebel is fine and dandy but for more serious use I'd recommend the 40/50D.
I disagree about starting on a manual focus camera. There is nothing inherently better about manual focus cameras that teach you the craft better than a digital. The reason they encourage starting on it is so you are forced to learning the discipline rather then taking the easy shortcuts that digital allows. But everything you can learn on an old manual film camera you can learn on a digital, if properly disciplined. Just dont use the dummy modes (anything that isn't M, Av and Tv) and do your homework.