I agree with other posters in that the Rebel XTi is more than enough to give you fantastic quality images with a little trial and error on your part. You should remember several things:
1. The most important part of using a camera is figuring out how to make it work. In the new digital cameras, the software or menu system is responsible for that. Just like a Nokia cell phone has different software than a Motorola (and to many people, it's superior), each camera comany programs their menus differently. You ought to spend half an hour in a camera store and look at the menus on the display, and see which are easier to understand.
2. What it feels like in your hands affects how well you control it. I'm sure with the competitive pressures of the camera market, Canon and Nikon are very close to each other in feel. The new pro-sumer cameras are amazingly light and comfortable compared to their analog cousins. But some controls are on the front, some are on the top, and some can only be accessed with the menus. Decide what you want the camera to do beyond point-and-shoot, and see how easy it is to set that task.
3. You cannot decide the quality of a camera by online pictures. This should be real obvious, but let's go into a little detail. First, each image you see on a web site was cherry-picked for whatever reason the poster decided was important. Second, the viewer (you) has no idea what compression was used to publish the image, but it was certainly degraded in it's journey from lens to internet. Third, all computer monitors look different, from soft to sharp, and from true colors to anything but; and the web creator has no control over your display. For example, at the most basic level, pictures shot by Macintosh users and published unaltered from their editing look way too dark to PC users because PC monitors display 20% darker than Apple monitors do by default. Finally, your camera captures up to 500% more image detail than a web page might display (if it's a 10-megapixel), but web publishers must "downsample" the images so they aren't 48" wide on a web page. This means you can throw away up to 90% of your picture detail and still have a nice image for the web. Look in a magazine to see how photos actually reproduce, not a web site.
4. Don't compress the image. There are settings both for image size (in pixels) and compression. Set your camera for both maximum image size and least compression, either TIFF or RAW. Once you make your images smaller and start to compress them, detail gets lost as the camera, not you, throws away good data. Wait until you get the photos into your computer before you edit the size of your pics.
I think you'll find that the only reason your pictures aren't award-winning with the Digital Rebel is because you aren't taking award-winning pictures yet! Brilliant photos are due to the time and care of the photographer, not the gear on his shoulder. You can break a plate with a hammer...or build a beautiful house with it. The difference isn't the tool, but the user. Save your money and get to know your tool.
Fact is, I took some amazing photos on trips in the last few years with a camera I ultimately decided was pretty junky...an 8-year-old Nikon Coolpix 950. It didn't have changeable lenses, had only 3X optical zoom, no aperture control and images were only 2 megapixels...basically a really heavy pro-level point-and-shoot. Nonetheless I shot some pictures that I'd be proud to publish in a magazine.
By the way, I now have a Nikon D50, a great camera that costs less than $600 these days. It replaces my $2000 F3, and I have no regrets. I haven't learned how to maximize it's performance yet either, but the more I learn the better I'll get.