> I feel the D60 and D30 produce better images than the D100.
What are your criteria? Straight out of camera? After processing? Noise at high ISO? The difference between the images out of the current crop of DSLRs (D60,D100,S2) is fairly small. I would argue that any one you choose can make great images. The person behind the camera is much more important.
That being said, the cameras do differ somewhat in features and out-of-camera results. If you're looking for nice out-of-camera results and a Nikon mount consider the Fuji S2 (or the Kodak 14n if/when it's released).
>but the cold hard truth is, I believe, the D60 is a better camera.
In some respects this is true. In others the D100 and S2 are superior. Depending on what/how you shoot, the D60 may be clearly superior for you. Without knowing what features are important to you, it's hard to make useful comments. Since you already have Nikon glass, it would certainly be easier to stay with a Nikon mount camera. In what ways do you see the D60 as superior?