This article contains information on tethering the Nikon D70 to Darkroom software.
The D70 is set by default, to be a MASS STORAGE DEVICE. In order to tether the D70 to Darkroom Software, the USB setting must be set to PTP (PICTURE TRANSFER PROTOCOL) mode. Consult page 165 of the included D70 Manual in order to set this option on the camera.
Note: The D70 USB port is USB1.1 and not USB2.0, so transfer of images is limited to the USB1.1 speed.