I bought a Nikon P90 that had horrible sensor noise. I exchanged it for a new one, and it’s sensor noise was even worse.*** That is a price you pay for stabilizing that 24X zoom in part by using high ISO. ***
Yep, I think SWAMPSNIPER is right as herein lies 'the problem' with that P90: High Sensitivity (up to ISO 6400). When I see ISO's up that high I cringe as I'd never push it that far as you're asking for noise. Which means I'd have to do a LOT of my shooting off Auto Mode.
It's like waaay back in the olden days shooting Tri-X (ASA 400) and 'pushing it' (under exposing) to 1600. You could get a lot of interesting shots otherwise not possible, but you're going to see a lot of noise with the slightest enlargement.
Noise is one more reason I went with the Nikon D3000 -- thanks to a slight Digital Education from SS here on FR when it finally came time to put down my Nikon FE for Digital. The normal ISO for the D3000 is 100-1600, and 3200 'expanded' -- which I've never yet used, and I get fantastic enlargements (They're framed and hanging on our walls).
My P90 noise is not because of high ISO settings. It is random pixel noise that gets progressively worse the longer the camera is powered up, and shows up as white spots (very similar to dead pixels in a CMOS video camera sensor) in the photos. The longer the camera is powered up, the more dead pixels that appear.