I'm going to dare to differ with Barry. I think the SX301 is heir to my first camera, the S2, a very high-end "point and shoot." I didn't take snapshots with that camera -- I shot on manual, learned all the functions, and was ready to move up to a DSLR when I had spent enough time with it. I had a show of my work and sold quite a few of my prints, and 90% of them were taken with that point-and-shoot. I took a class in which all the other students had DSLRs, and when we got to the point of showing and critiquing our work, the teacher called everyone over to look at my pics, saying "See what you can accomplish with a point-and-shoot?"
If I sound a little cranky, well, I guess I am. There's a lot of snobbery in the field of photography, and much of it has to do with equipment. (I was completely snubbed once by someone with a tripod and big lens at a lighthouse, when I said "Hi," point-and-shoot in hand . . . a lighthouse that I had taken literally thousands of pictures of, sold some, been published in a calendar, etc. etc.) I think that a good P&S can be an excellent vehicle for a first-timer to learn on, because it's easy to get very frustrated with all the balls you have to keep in the air with a DSLR. You can find out whether you're really interested, really serious, before you step up to the money pit that yawns open the minute you buy that Rebel XT.
Will you be limited with a SX301? Sure, but it will take a while to figure out what the limitations are. Would you take "better" pictures with a DSLR? Sure, in time. You'll also be limited with a Rebel, eventually, and want to move up that ladder too. I suggest you check out the camera finder on flickr -- the SX301 isn't on there yet, but the S5 is (which I think it's replaced), and you can see the pictures taken with
that camera and see if you can live with them. Look at the pictures from the Rebel, too, and see what you think of those.
I'm sure you'll enjoy whatever you wind up with. There's so much to learn and so much fun in the process.