Well the D7000 is going to be about 300 more than either the D90 or the D5100. I still like the AF on the body, again because you can save money on certain lenses down the road... Between the D5100 and D90, the D90 is a little closer to a 'pro' body. I really like the ability to change the settings on the fly with the D90. There are 2 adjustment wheels and your major options (ISO, f/stop, AF, shooting mode, metering, along with quality and white balance) are all changed from a holding down the correct button and spinning the adjustment wheel. Where as the D5100, you have to go through the menus to navigate most of those options. The D5100 just seems a little more gimmicky with the moveable LCD screen, and the built in HDR mode. The D90 has auto exposure bracketing, so you can HDR on the computer.
They both have the ability to shoot video, the D90 is 720p but only autofocuses once, but the D5100 is 1080p with full time auto focus. Not sure how many videos you plan on shooting, but the D90's is more than enough for me.