I am using a D80, and i also owe a 70-300VR FX lens.
I mounted my camera on a tripod and did a 70mm shot using the kit lens(DX lens) and the 70-300 FX lens, the picture came out are identical. the position of everything in the picture are totally the same.
DX camera just produce picture smaller than your normal 35mm size picture, its like a 35mm picture and u just crop out the center portion. the field of view is just part of the 35mm picture size, the size is very much similar to the view of a focal that is 1.5x of that u use but its not really that focal length
what ever lens u use on a DX body there will be a crop factor for sure.
have yet to try as i dont have a FX camera, but i believe that what u see on a FX picture of let say 75mm is different from what the picture of a DX camera using a 50mm lens in which after the crop factor of 1.5x is suppose to be 75mm.
i think DX lens are just normal lens like FX lens in terms of focal length but design to focus a smaller image compared to a FX lens.