professionally cleaning camera?

[MarshallG]

It's easy to tell if a sensor needs cleaning. Just set focus to infinity and photograph a white piece of paper. You want the paper totally out of focus. Any sharp black objects you see are sensor dust. If you find dust and you have a second lens, you can repeat the experiment with another lens, to prove its not lens dust.

If the dust particles are really small, just use the camera menus to register the Dust Delete Data (or whatever your camera calls it). This will automatically remove the dust spots from your photos.