Response to Neal C. and Matt A.
Dennis P.

Neal C. and Matt A., I'm afraid that you are getting your descriptions of Orcs from modern sources, like Warhammer and Dungeons and Dragons.   Remember, this movie is based on the works of J.R.R. Tolkien.  He describes the orcs this way:

" These were the Orcs, a multitude brought forth in shapes twisted by pain and hate. The only joy in these creatures was in the pain of others, for the blood that flowed within Orcs was both black and cold. Their stunted form was hideous; bent, bow-legged and squat. Their arms were long and strong as the apes of the South, and their skin was black as wood that has been charred by flame. The jagged fangs in their wide mouths were yellow, their tongues red and thick, and their nostrils and faces were broad and flat. Their eyes were crimson gashes, like narrow slits in black iron grates behind which coal burn. "

This description comes from an excellent article that can be found at www.tolkien-archives.com, and is based solely on Professor Tolkien's works. 

However you may imagine the Orcs to look, I am fairly sure that Peter Jackson is relying faithfully on Tolkien's description, rather than your's or my imagination.