Best type of 50mm lens for a D90?

I'm buying a Nikon d90 body in the next few weeks and would like to start of shooting live music with a Nikkor 50mm lens, i want to get a 1.4 for those low light situations but on ebay there's a few different types of Nikkor 50mm lenses

Eg

Nikon Nikkor AF 50mm 50 f/1.4 D

Nikon AF-S Nikkor 50mm f/1.4 G

So i'm guessing one is a older model and one newer? What one would you guys suggest for a d90?

Buy the newer design AF-S lens. Even though I have the older D lens, I still think about buying the G lens. The nice round bokeh goes away very quickly with the D lens. The G lens has a "rounder" view due to the new design of the aperture blades.

If you look at you will see what I mean. The two shots in the top row are made with the 50mm f/1.4 D lens. The one on the left is wide open. The one on the right is only at f/2.8 and the "circles" show seven sides already. The G lens has nine aperture blades and they are shaped in such a way to keep the circles looking round.

Not to mention, the AF-S probably auto-focuses just a bit faster (not that the D is slow) and it should really be silent (not that the D is loud… ).

Before going for the camera you yourself have to decide which sort of photography that you're going to do with. Digital-SLR are most commonly used by the professional photographers and some other point and shoot cameras also provides multiple functions like in Digital -SLR + Compact (Both) in 1.
To learn the basic about different photographic situations and compatible lenses visit the site
http://mounteverestandtrekkinginformations.blogspot.com/2009/11/canon-travel-photography.html
different topics included within the site may help you to find your answer in detail I think, thank you.

I recommend the 50mm f/1.8G AF-S or 50mm f/1.4G.
You can also use the older 50mm f/1.8D on the D90 because your camera has a built-in focus motor.