don't buy that camera Z, here you've got the example that Sony should do just TVs and playstations
I would still buy any canon or minolta cameras, except D70 I have no idea about nikon...
anyway, I would first try to read some reviews about cameras you've put to the "final round" (I mean reviews from profesional photographers, not the ad reviews) and then compare and decide, which suits you most
good luck with choosing!!!