I agree with others as far as the versatility of the 18-200. I recently bought the VRII model and love it. As others have said, it lives on the camera 90% of the time and I rarely even bring out the 70-300 for the extra 100mm.
The back LCD on my D40 is on the fritz and often gets stuck just displaying the negative colors so im contemplating possibly getting a D90 or D7000. Im curious as what others will say about their comparison.
As far as glass goes, you cant go wrong with the Nikon 18-200, its a great lens and very versatile, I love it for traveling. Whether you need to be on the wide end to take in the landscape or on the tele end to shoot wildlife, this lens will do it. VR and AF are great as well, i strongly urge you to go for the Nikon model and not the Sigma, Tamron, etc. The 50mm is fun too. The 1.4 takes some beautiful shots but the 1.8 is a lot of fun too and very affordable.