"I have started to get paranoid for the first time, since when I started using my DSLR (D90) back in 2009, I had little or know concerns until I got the D7000 during last year."
Don't get overly concerned if your sensor is not perfectly clean John. As I mentioned in my posts above, what dust you do see, is easily removed with the Healing Tool or Clone Tool or a combination of both, in either Photoshop Elements (version 7 to 11) or Photoshop CS (versions 1 to 6).
In smaller JPEG files for the web and email where the resolution is less (typically 72ppi), dust specs will be harder to see (as evident in my first pic above which was 900 pixels wide at 72ppi). Dust contamination only becomes more evident when making prints at 5x7 or larger, especially if the original NEF or JPEG file has been substantially cropped and enlarged.