I've owned a D60, a D90 and now a D700.
The D60 was great but I soon realised the limitations.
The D90 blew it away and the pictures I produced tell as much.
Then I soon realised the limitations of the D90 and bought a D700.
The D700 blew it away and the pictures I produced tell as much, although not as much as the difference between the D90 and D60.
Of course, having pro spec glass helps as well. But having started off with a D60 and 55-200mm non-VR and now having the D700 with 24-70, 80-200 and 50 1.4, I'm confident enough to say that the D60, even with any of these lenses attached, wouldn't come close to what I get with the D700.
Remember, the question isn't asking if better kit makes you a better photographer, but some people do outgrow their kit fairly quickly. It all depends what you do and how serious you are about doing it I guess.