Dude i dont mind answering but you will need to do some homework if you want to spend 1K

AF-S have focusing motors IN THE LENSES while G and D uses a focusing motor on the camera.... so if you camera doesn't have the focusing motor it (d40), the lense looses it's AF capabilities. that is amoung alot of other things BTW... like D reporting focussing info to the camera.

Bottome line is you will be ablke to find alot more used AF lenses for a D70 then a D40.