Jen,
Wait, just a few days!!! Nikon and Canon are rumored to be announcing new cameras on March 8 and 9. Now, it might be just the new interchangeable lens, mirrorless camera from Nikon--but it also could be the new D900, or something like that...
...now, I know there are brand new rebates on almost all the higher-end Nikon bodies, and the D700 has dipped to $2,399 after rebate, but if there is another Nikon body announced, and there could be one, because Father's Day and summer vacation and graduation make up the second-largest camera sales period of the year, you could have a major case of buyer's remorse.
Some people speculate that Nikon might put a full-frame sensor in a D90-class body, to have a camera comparable to the Canon EOS 5D or 5D-II, for a lower price than the 5D-II. Full-frame, but a light,simple body with a 12 MP image sensor, and at a price low enough to undercut Sony's $1899 full-frame body.
As far as lenses go: the D700 will automatically switch to DX format capture size when a DX-Nikkor is mounted on it. The 18-55 will probably not cover the full FX frame at the wider end, but I think it might at the longer end. And the 55-200: telephoto lenses do not have a large image circle, so I think it ought to do okay on a D700. As far as needing "top-quality glass", that's more of a myth than a reality. A large, full frame sensor with huge pixels due to a 12-13 MP sensor pixel count can turn in QUITE excellent results with only "good" lenses from the 1970's or 1980's because the sensor size is roughly 2.25x larger than a DX Nikon sensor is; small sensors depend hugely upon ultra-high lens Modulation Transfer Function ie--high resolving power and high contrast lens delivery to the senor, but a bigger, full-frame, low-pixel count camera like the Canon 5D, Nikon D3 and D700 series cameras---those cameras do good work with lenses that are NOT ultra-high-quality because the sensor is bigger, the pixels are bigger, and the results do not need to be "enlarged" nearly as much.
With a D700, you could do okay buying old, 1990's AF-D Nikkor lenses, and still get great pictures. That was one reason the original Canon 5D was so,so good: a 12MP full-frame sensor hits the sweet spot on multiple counts. BIG pixel wells, so good High-ISO; low pixel density, so forgiving of lens MTF deficiencies, and almost any lens designed over the last 30 years is adequate to excellent.