If you want to have 景深, the aperture must be large, if you buy D40, you need to use AFS lens, provided that you need large aperture to achieve good 景深, here are your cheapest choices:
17-55/f2.8, $9980 or
prime lens 105mm VR, $5500
If you buy D80 which can use AF lens, you will have many lower prices choices, such as:
$200 for a SD card, $300 for a extra battery and $2680 for SB800. Total: 13K. No need to upgrade for the next 5 years........ unless you really want to.
In terms of control, D200 is much better than D80, it has all the setting switches outside the body, you almost no need to go to the menu for everyday shooting. For convinence of control, I realy can't think of anything to improve for D200. It's very similar to D2X already.