I have two Nikon D2's (D2X and D2Hs) of these I prefer the Hs. What you get with any D2 is magnificent build quality, fast and accurate auto-focus performance, true and accurate colour balance, etc. Megapixels are not that important. As mentioned before glass is more important but the above features are also.
The main reason my I went for a Hs is total compatibility with D2X with operation, batteries, memory cards but above all amazing low light performance.
Sample photo at ISO1600 with challenging coloured lights
http://www.airliners.net/open.file/1213781/L/
Check out my gallery with EXIF so you can see the D2Hs ones ->
http://www.worldphotographyforum.com...500&ppuser=101