Your stack of Nikkor's sound awesome! good spread for astrophotography
The D700 will be right up your alley... I think the Canon 5D is the direct competition for the D700..
my problem... I love nikon bodies... But canon L glass has me hooked...
If someone makes an adapter to go from nikon body -> canon EF lenses whilst retaining all automatic functions (and IS/VR) I'll have a D700!!!