The U.S.S. Enterprise NCC-1701 during Christopher Pike's years in the ship's command.
Based on the 1st pilot episode filmed for "Star Trek: The Original Series", titled "The Cage". This episode was known to contain footage later used for flashbacks in the series' only two-part episode, "The Menagerie" (which altered their color scheme to full color).
Although I found the screenshot used for this wallpaper in color, I used Windows Live Photo Gallery to change the color scheme of it to black and white in order to give you, the users on this site, a feel of how the "Star Trek" episode was originally shown before appearing in a color version.
Hope you all like this piece!