Every new body has a new version of NEF and requires an update to convert it.
I used to use the old Capture NX as my converter for my D200 and needed the newer NX1 to convert my D300 files. I also needed to upgrade from CS2 to CS3 to open the D300 files. I would guess that Adobe ACR in CS3 will get an update for D700 files but I suspect you will need to upgrade from NX 1 to NX 2 to open a D700 NEF even though it uses the same sensor and EXCEED processor as the D3.
The irony is you need to buy a converter from the company that sells the camera to get the results the manufacturer intended. At least for a short time NX was free with a camera but got many hooked on NX and now many are upgrading to NX2
Albert J Valentino Nikonian Moderator Emeritus Vantage Point Images Mastery of Composition is the Key to Great Photography