This is for the original poster: I know the D40 and D60 are available at *very* attractive prices right now, but the D60 has basically been supplanted/replaced by the D3000, which has 11-area autofocus with 3D focus tracking, basically moving you up to the D90-class autofocusing system, which means the Multi-CAM 1000 AF module,instread of the Multi-CAM 530 module used in the D40,D40x,and D60.
My experience with Nikon bodies is that the higher the focusing module number, the better the camera works with the lower-spec'd lenses, like the kit lenses and slow consumer zooms like 70-300 and other slow, variable max. aperture zooms. When using top-level,pro glass on the D40 (70-200 2.8, 300/2.8, 200 f/2), those lenses focus very fast and reliably on the D40. But with something slow, like the 55-200 on the D40, the weak AF module is not so hot as it is with pro glass. So the conclusion might be, with consumer and kit-level lenses, it pays to go for the more-sophisticated,more-capable AF module bodies, like the D3000 and "up".
I personally prefer an AF system that has a reasonably wide coverage of the frame,more so than an AF system that is highly centrally-biased.