If you enjoy macro and natures stuff, the 10D will be more than enough! You can easily use a point and shoot for that stuff

. 10D puts out some awesome pictures and well, so does the D70s. Tough choice. I went canon because I liked their lens line up. I believe they have more to choose from in different price points as compared to Nikon.
Going used gives you more money to spend on lenses

. My 10D is also for sale for a pretty good price if you're looking for one. (small plug)