I recently upgraded my D60 to a D90 so I can definitly share my homeworks
Reason I was looking for a new body:
1- wanted better picture quality in high ISO (i realised I shoot a lot inside and during evenings. My brother is also a musician so i tend to shot some shows from time to time)
2- wanted a better focus system (was looking for more than 3 "big" focus points)
3- wanted the ability to use my SB600 wireless (now I want a second one hahaha)
4- wanted a better display on the camera and the ability to see the histogram for each color.
5- wanted to access my settings faster on the camera and spend less time in the menu.
D90: 1-2-3-4-5
D5000: 1-2-4(for the histogram, not the monitor)
The real question in my opinion is: "Do you shoot in P A S M mode or mostly rely on the scene/auto mode"?
You can definitly shoot in manual with the D60/D5000 (I rarely use anything else than P A S M on mine), but I beleive this is where the D90 features shine over the D5000.
- Ability to use the built-in flash as a commander. It can be a lot of fun playing with different source of light. (you will need to upgrade your SB400 to a 600 at least to do that)
- The Information display on top of the camera is usefull and "looks cool".
- Ability to use more lens (not an issue if you are only using AF type lens)
- Ability to change ISO/Aperture/Shutter and many more settings right on the body instead of going into the menu (the biggest advantage in my opinion).
The D5000 on the other hand as the following scene to choose from :
Night Portrait, Close up, Sports, Child, Landscape, Portrait, Night landscape, Party/indoor, Beach/snow, Sunset, Dusk/dawn, Pet portrait, Candlelight, Blossom, Autumn colors, Food, Silhouette, High key, Low key.
I honestly rarely use the screen for framing since using the viewfinder helps me getting in my bubble so the swivel was not an attraction for me.
So it all depens what type of photographer you are. I don't beleive one is better than the other. Dress a list of what you are looking for in a new body and the answer will come faster. Kirbinster bought one because due to the weight factor. Maybe it's something you are looking for. Are the few different features worth spending 230$ CDN more for a D90 ? For me it was.