Nikon has 3 Nikon 70-300mm Nikkor Zoom Lenses in it collection:

Nikon AF Zoom-Nikkor 70-300mm f/4-5.6G
 
 
 
Lens Specs
SIC, D, G

Lens construction
13 elements in 9 groups

Minimum f/stop
f/32

Maximum aperture
f/4.5-5.6

Minimum Focus Distance
4.9 ft.

Attachment/ Filter Size
62mm

Weight
16.5 oz

Dimensions
2.9 x 4.6 in.

This lens will not work with the Nikon D40

Nikon AF Zoom-Nikkor 70-300mm f/4-5.6D ED
 
 
 
Lens Specs
ED, SIC, D

Lens construction
13 elements in 9 groups (1 ED Element)

Minimum f/stop
f/32

Maximum aperture
f/4.5-5.6

Minimum Focus Distance
5 ft.

Attachment/ Filter Size
62mm

Weight
18.2 oz

Dimensions
2.9 x 4.6 in.

Nikon AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED

Lens Specs
ED, SIC, IF, D, G, SWM, M/A, VR

Lens construction
17 elements in 12 groups (two ED glass elements)

Minimum f/stop
f/32-40

Maximum aperture
f/4.5-5.6

Minimum Focus Distance
4.9 feet

Attachment/ Filter Size
67mm

Weight
26.3 oz

Dimensions
3.1 x 5.6 in.

The question is, which lens should you get? The G version, the ED version, or the VR version. There are a couple of factors to consider, price, and quality. The G and the ED are very close in respect to quality, if you look at the MTF Charts (G lens vs ED lens) on nikonimaging.com website you’ll see that they have very little difference in lens performance, so you have a choice between cost. The G lens costs less then the ED version. Now the VR version packs a few more additions and enhancement to its package, but it also brings a heavier price tag. The VR version does have the Silent Wave Motor, Vibration Reduction, and the MTF chart show a higher performance. So it depends on what you’d like to spend and which camera you own, at least for the Nikon D40 owners. Just remember the G version doesn’t work with the Nikon D40 DSLR Camera.