The Canon & Olympus lenses ain't gonna perform too well on a D50
The Nikkon 18-70 is on my shopping list - I plan on picking up a used example from one of the multitude of D70 owners who are upgrading to the 18-200 VR.
I am aware of it's limitations, and will be buying it for it's wide-angle abilities, not telephoto. Yes there is some vignetting, but as someone else pointed out on here recently, it's not likely to be a real-world problem unless you happen to take nothing but photographs of white walls in bright sunshine
D300 | MB-D10
18-105MM F/3.5-5.6G ED AF-S DX VR | 105mm f/1.8 AI-S | 70-300mm f/4.5-5.6G ED-IF AF-S VR | 80-200 f/2.8 | 50mm f1.4 | SB-900 | SB-600