Hi Roger, I have been using one of these for 2 years. I think it is good value for money, but take into account you will most likely want extra lenses which add to the cost. Mine came with a 75-300mm Zoom lens (no IS) and the EFS 18-55. Since then I have purchased a 60mm macro and the EFS 17-85mm which I find is a good 'walk around' lens and the one I use most. Add to that optional lens protectors and filters and the cost rises dramatically.
There are good reviews here HERE and HERE
Is your $90 a point and shoot ?(you have done very good work with it)
The Rebel XSi is a good entry level dSLR but I would advise anyone to be more certain than I was about making the leap :) I often prefer to use my Panasonic FZ28 - much easier to carry around and no hassle of changing lenses. It has 18x optical zoom, can shoot RAW and also has video, something the Canon lacks. But I am a lazy photographer :)
The Rebel XSi is very comfortable in the hand and is comparatively light. If you know anyone who owns one try to borrow it and get the 'feel' of it - see if you are comfortable with it.
The 'Live View' capability many people find particularly useful. Good description of it is HERE
My overall opinion after 2 years use ? I am totally satisfied with it. For me it was a steep learning curve, and I still do not use it to its full capacity - but the capacity is most definitely there.
Hopefully someone with more experience in the dSLR area will add their opinions.
Good luck with your decision - and whatever you decide on - have fun with it:)
I got my XSi last October and have been very happy with it. I skipped the kit lens, so I can't speak to that. So far, I've found it to be comfortable and easy to use. The controls are accessible and intuitive, as well. I opted for two prime lenses - the 50mm f/1.8 and the 35mm f/2.0. I use the 35mm 99% of the time. With the 1.6x crop sensor, it makes for a good normal lens which is what I wanted. Plus, it's super lightweight, and the f/2.0 has been a lifesaver in low light.
Good luck deciding! I think there are lots of good cameras out there. It's largely a matter of feel/preference and finding a match for your needs. Let us know what you choose. :)