Good run-down of the Canon Digital Rebel and Nikon D70s in this article by Philip Greenspun.
Digital single-lens reflex (SLR) cameras are the standard tool for serious photographers. With the recent introduction of cameras such as the Nikon D80 and the Canon Digital Rebel XTi the market for digital SLR cameras has expanded tremendously. A point-and-shoot compact digital camera can offer reasonably good image quality but a digital SLR, which usually looks a lot like an old standard 35mm film camera and may use the same lenses, offers the following advantages:
* accurate, large, and bright optical viewfinder
* fast operation and large controls
* excellent image quality in low “available” light situations when it is necessary to use higher ISO speeds
* interchangeable lenses
When I was looking for a new camera I first went to the point and shoot digital types for portability and weight. Then I after weighing the pro and cons I landed on a Canon EOS 20D, it was such an awesome camera and light. Last year I upgraded to the Canon EOS 5D and now shoot stock photography with the camera and have been sucessful with it. I recently purchased a Panasonic lumix DMC-LX2K 10.2 Mega pixel camera and have been very disappointed it was only one of the few point and shoots that shot RAW files. It kept terrible focus and I was not impressed with the files it produced. I love my 2 digital SLR cameras.
My two cents.