if something or someone is running around I find it incredible hard to use a tripod, because even if you have the best super-tilt&swivel-head, you want to change perspective, move around in the room, shoot from above or near the floor. That'll never
work with a tripod!
So if you're saying that you'd like to photograph a moving 2yo you have to be able to move around with him/her and you're probably shooting indoors with available light.
There you have it: These are classical situations where image stabilization is invaluable! So consider the Nikon 18-200mm VR. It also solves the problem of changing lenses, loosing valuable time, getting dust into the cam-body, carrying another lens with you.
If the price is a bit steep there is the brand new AF-S VR DX 55-200mm 4.0-5.6G IF-ED which can be had for around 300EUR.
But think again: the necessity to switch lenses back and forth at 55mm or 70mm in photographing young children will come up frequently and you really risk loosing valuable moments
P.S.: In general the zoom range of 18-135mm covers quite a lot of opportunities and the quality should fit your needs - but the lens lacks VR...
P.S.2: In the meantime the D40x came up, giving the same 10.2 megapixels as the D80! That could be an alternative for you. Unfortunately, they seem to sell the D40x only as a kit with a basic lens. That is certainly not a good proposition if you a aiming at the 18-200mm VR...
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews
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