Here are 18 Windows7 Themes on the subject of Dragons. The artist is KeremBeyit, whose gallery appears in Deviant Art.
You can download the theme from the Artists link by selecting Download Center, and typing in the theme name. Note, words are separated by a hyphen.
Here are the images:
[Over the Clouds], [Sir Wooden Sword], [The Well], [Black], [Mushroom Hill],
[Half Elf Girl], [Into the Unknown], [Go Away], [Steampunk Dragon], [Moonlight],
[Egg Thief], [Bronze], [Red], [The Dragons of Ordinary Farm], [Green], [Silver],
[Cretaceous Sunset], [Forest Girl], [The Book of the Sword Cover]
The artists web site: http://kerembeyit.gfxartist.com/
To convert Wallpapers to Themes go to: How to turn Wallpapers into Windows 7 ThemesMore Galleries: All Galleries | Windows 7 Galleries | Windows 8 Galleries