Would a nikon d200 be a good upgrade from a d3000? Or should I just get a d90?

Upgrading soon. Also thinking about the d5100? The d200 seems the most professional.

I have and love my D200.It's a magnesium-bodies, professional grade DSLR with a vast array of settings for the seasoned photographer.

That being said, I'd go with the D90. Going from a D3000 to a D200 is like going from an automatic compact car to a Kenworth bigrig with a 10-speed manual transmission. You'll spend much of your time missing shots while trying to figure out the controls.

Now a D90 is a great next step. The D90 actually has image quality comprable to my D200, and has something you'll most likely appreciated. The D90 has a mode dial with A, S, P, M, Auto, Sports, Close-up, Landscape, Portrait, and other selections. The D200 has A, S, P, M, and Auto. The D90 has a better lcd screen, Live-view, and can take videos.
http://www.kenrockwell.com/...on/d90.htm

In fact, the D90 even beats out the D300 in some ways, as it uses newer technology for processing the identical sensor.

The D5100 is a very good camera that further raises the bar. It is capable of even better images than either the D90 or D200.It adds an articulating lcd screen, and full-time autofocus with HD video.
http://www.kenrockwell.com/.../d5100.htm

Bottomline: I'd handle both a D90 and a D5100 and see which one fits you and your style.

D200 is much older, therefore has more noise, no video (though useless if you don't need it), and misses a lot of nice improvements.

D90 is excellent, D5100 has a little bit less noise, better video, articulating screen and that's it. I'd get the D5100, or D90 if you want something bigger and rougher!

Here's a DSLR Buying Guide - http://www.the-dslr-photographer.com/2009/11/which-dslr-to-buy/

D200 is a very capable body. The only negative point is the older image processing.

If you click raw(nef) and do post-processing, then D200 is a far better option than D90. With D200 you'll be able to use a vast range of old manual Nikkor lenses too with evaluative metering, aperture priority mode etc.

If you want to click jpg then opt for D90.