Need opinion on Nikon D-90 Camera?

Hi
I'm new to DSLR camera. I have used Cannon SX 20 is in past and worked a lot with its manual mode as well.
I want to upgrade to Nikon D-90. Other options I have are Nikon D5100, Cannon 550 D and 600 D.

But my prefernce is D90.

I have a confusion here. Nikon D 90 is kinda obsolete. I don't want to upgrade my new camera model for next 5 6 years (will surely add lenses though.
Is it ok to still go for D-90 seeing that it is obsolete.

This is quite a tough question.
If you are just using the camera for taking photos then I would choose the Nikon D90 it wins HANDS DOWN on build quality anyone who says otherwise is an idiot.
If you are going to make movies and for cropping I would choose the Canon 550D You have 18MP to work with (The 3 Year old Nikon D90 only has 12MP)
The let down with the budget Canon DSLR cameras is the build quality. For some reason Canon like to "Cut corners" on there budget DSLR range. If you don't believe me hold a Nikon D90 in your hands then hold a Canon 550D in your hands.
So in a nut shell…
If you are mainly using the camera for taking 2D Stills then choose the Nikon D90
If you will be making movies and doing a lot of cropping in your pictures then Choose the Canon 550D

Canon EOS 550D and 600D have the same sensor, so if you don't need the articulating screen (which is useless on DSLRs for now) I'd get the 550D. You save money and can later get a new lens.

D90 is indeed obsolete, but it's still a great model.

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

The D90 is not obsolete. It's just old. Go for it.

The Nikon D5100 provides several notable upgrades over the D5000 making it, in our opinion, a far more attractive package than its predecessor was at launch. Significantly smaller and lighter, it's also easy to use and capable of delivering consistently good results. Our only quibbles, such as they are, are fairly minor and limited to the exclusion of useful advanced entry-level tools such as the ability to the pop-up flash as a wireless commander and the omission of a depth-of-field preview button. Both of these would ultimately prove more useful and give the camera more longevity than any of the Special Effects shooting modes. Overall though, the D5100 is a great camera to use that's capable of delivering stunning images. If you're in the market for an advanced entry-level DSLR be sure to add it to your shortlist.