Need advice on first SLR

[Amber J]

I am looking to buy my first SLR camera. I only know the basic SLR jargon but am eager to learn more. With pocket cameras I like to shoot landscapes and night photos. The qualities I find most important in an SLR camera are:

-dust control
-image stabilization
-fast multipoint autofocus
-low noise at high ISO settings.

Bulkiness and the ability to shoot HD video doesn't really matter to me as I already have several other smaller cameras and an HD camcorder. I have a camera that has 6 megapixels so any camera above that is fine, however, I'm not obsessed with getting a camera with extremely high megapixels.

I've been looking at Nikons. I am somewhat confused when it comes to the differences of the D5000 and D3100. They are so similar so I want to get some opinions on them from owners.

I would love to get a D90, it's just a matter of money.

Any recomendations and insight would help greatly! Thanks!