Shot professionally for years when I was a younger man. Also ran a camera store. Could shoot whatever I wanted to for free.
For slr's I still shoot nothing but Nikon. Superior optics. If you can afford the D90, go for it, I promise you won't be disappointed.
Also, do not get drawn in to the megapixel wars. It's common to find higher quality images in cameras with lower megapixels. In addition to lens quality, the sensor makes a huge difference.