one important thing, whatever u pick, u not only pick up a camera instead you pick up a system. the lens and the flash unit. for example, if u have had some canon lens, u probably will go get 350D. other factors include the lens cost, quality, customer service etc.
try to hold the camera urself and feel both of them. if u have a big hand, go get D70. i do not have a small hand, and feel D70 fits my hands better, and the exterior material feels much better than Canon 350D/300D.
it is a personal choice, but u would not go wrong with any of those.
good luck!