TS... since you are using the Nikon, I am assuming that you are familiar with the Nikon already. Why don't you consider a D700. After the release of the D800, I am expecting to see D700 thrown out in the BnS section and will be quite affordable.
The D700 would have a better focusing system as compared to the 5D classic (or even the 5D mkII), it is also a FF with BIM so all your lenses should be able to work, no problem at all (unless those lenses are designed to be purely manual), one setback is that D700 can't take movie (but I believe 5D classic can't take movie too - not too sure).
If taking movie is a must for you, then I would recommend the D7000, which is a beautiful camera too, with good weather sealing, great high ISO noise handling, excellent pic quality, large buffer and high speed, also take excellent movies (full HD I believe).