I'm not sure how the D2x image quality is, but since its nikon's flagship camera, im sure its pretty good. If you compare the ergonomics of the d2x with the 5d the nikon wins, it just feels more solid, and the controls are better in my opinon. I have the 5d and a 1d, and my 5d sometimes feels like a toy compared to the 1d, you have to see if thats something important for you.
Looking at the lenses you have, I would suggest getting the following instead,
17-55 + 70-200VR. Both are superb! Or if youre a prime nut like me, I would suggest getting the 85f1.4, its suppose to be a killer portrait lens. A smarter approach though would be to find out what photography you'd like to do, and get lenses specific to those interest.
If you do go 5d, now is a great time to get it. There is a double rebate from canon, and you can save $700 if you get the 5d and one of the lenses on their rebate list.
Remember though, the camera is just a tool.