[Osprey]

Nikon definitely has momentum in the DSLR market now. The D3 and D300 look to be extremely good. Canon is famous for its expensive, white telephoto lenses, while Nikon is generally well regarded for its lenses. One of the bigger indictments of Canon was that for a long time (and it may still be), the best wide angle lens for the Eos 5D was a Nikon 17-35mm 2.8 used on an adaptor.

Also, Nikon offers a quite good 18mm-200mm lens with image stabilization (VR), that can be used as a one lens solution if you're not interested in multiple lenses.

However, I would go handle the bodies and see what feels good to you. I am a Nikon user and for me I would have to get quite a high end Canon body before they don't feel like cheap plastic or have a viewfinder like a tank slit. For instance, for the same price, the feel of the D200 was much better than the EOS 30d or 40d.