I have been using digital camears for awhile, with my latest being a Fuji with an 18x zoom. I am disappointed with missing shots because of the slow shutter, and have been salivating over the Nikon D90 -- the only thing holding me back: will I be disappointed by not having a zoom? (the 18-105, or even the 18-200, will only give me about a 3X zoom, right?)
I see. One of the drawbacks with the 18-200+ types of superzoom lenses is that they tend to have smaller apertures which will also give you somewhat slower shutter speeds at the same focal length compared to a lens with a smaller range.
Sure, the 18-105mm with its wide angle to moderate telephoto should cover muost of your general photography needs. Won't help with birds though. I used a 15-85mm when I visited China and it was a great range for travel. Of course YMMV (depends how much you use the long telephoto end).