I'll just ask... Why a D3 over a DMK III

Before everyone bashes my question, let me clarify.

I have been a Canon user for years shooting mainly kids field sports adn surfing. About a year ago, I got out of photography and sold all of my equipment.

I am now looking into buying a camera and a 400 f/2.8 lens and assumed I would go with the newest Canon. After asking around, several people told me to give Canon a real look again.

That said, considering I am starting with nothing, why should I go with a Nikon D3 and related 400 f/2.8, over the Canon equipment?

Thanks for the input.

Calfee