Re: Canon D20 vs Nikon D70
I was also between the two, I think in the end I will go with the 20D because it has a faster shutter speed and it has 2 more megapixels than the Nikon. They both cost around the same anyway so I think its a no brainer.
Canon has a lens kit (includes body also) that you can get for not much more than the body kit alone, and I am pretty sure that Nikon has the same thing. I forget which lens it comes with but I imagine it would be a pretty good all-around one. (17-55mm?)
Re: Canon D20 vs Nikon D70
One thing to remember is how fast new DSLR's are introduced. When you buy one, you're buying into a system. They're both good systems with tons of lenses and accessories, but I'd recommend going to a camera store and taking both for a test drive. See how they feel in your hands because they're designed to work like each manufacturer's other cameras. Basically, get used to one brand and the controls on another model of camera body will work a lot like other bodies they have.
I don't think you can go wrong with either, but the 20D is a step up from a D70. Nikon has a D100 which has been around for awhile and probably due for a replacement early next year. That camera would probably be a better comparison, but you can keep waiting forever with these things! I have a 6mp (Fuji S2) and have gotten 16x24 prints that are amazing, and 24x36 that are really good. Two more mp isn't a bad thing, but depending on your use it might not be necessary.