Osiris...you can't go wrong with Nikon....

I noticed in the write up that the battery for the A100 is exclusive to that model. That usually gets my bells ringing.

I don't have experience with the Sony and I'm just going with the write up on it, http://www.dpreview.com/reviews/sonydslra100/ but for my money...NIKON. It's what the pros use mate and you can get a seriously nice camera based on what the pros use but made more for regular joes like you and I.

Good luck.