You forgot to factor in what Nikon does as well.
The D700 already has a 51 point system which is IMO better than everything currently available on the market besides the 1DX
Not really. As I've stated before, the real competition between the two companies plays out on the battlefield of P&S cameras and entry-level dSLRs. By the time comsumers are considering a high-end or pro body, most are invested in a system and inertia means they won't switch (empty threats on internet forums notwithstanding).
Why is the D700's AF better? It's got 51 points, but if that's the basis, then more MP automatically make a camera better, too. Physics and geometry tell us that the wider the baseline for a triangulation measurement, the more accurate the measurment. AFAIK, all Nikon AF systems use f/5.6-sensitive line sensors. Canon systems have up to f/2.8-sensitive line sensors, which are more accurate than f/5.6-sensitive points. Just one more thing to consider...
More is definitely not better but in this case I would take Nikons AF system over the 19 point in the 7D which people have been clamoring for.
I own a 7D. Have used a D700 and a 5d/5d Mk II. D700 AF is much better in low light than the other 3 (Canon 7D, 5D II, and 5D. That said I have not used the 1D Mark IV or 1Ds Mark III so am unfamiliar with canon's 51 point system.