If you're buying now, there's no doubt which one to go for ... D70. It's much more capable, and cheaper, than the S2Pro.
And this is coming from someone who's shooting with an S2Pro ! :bsmilie:
But the S2Pro has some good points as well, eg. can do proper 3D TTL flash with all Nikon Speedlights, while the D70 can only do i-TTL with SB600/800, I think. But I could be wrong ... read up on it over the internet, lots written about both cameras.