Photoshop elements is what you need, even better is Lightroom 2. Lightroom is amazing and does everything photoshop does in a easier layout.
Photoshop and Lightroom will have to have the latest updates to open the D90 raw's as there a new file type with it being a new camera.
Ignore the comments about the D90 not being an entry level camera, it's easy to work with. Just learn what A, S, P and M do and shoot away. Excellent camera, I have one
. Want any tips / help feel free to PM me.
Ben