Several reputable software hosting sites provide these themes for free. Be sure to select the version that matches your system architecture (32-bit or 64-bit):
Offers a 4.4 MB freeware pack with 10 HD backgrounds that fit almost any screen resolution. batman the dark knight theme for windows 7 free download
Transform your desktop into the gritty, atmospheric world of Gotham City with a . Inspired by Christopher Nolan’s cinematic masterpiece, these free personalization packs replace standard Windows aesthetics with brooding visuals, custom icons, and immersive soundscapes. Top Features of The Dark Knight Theme batman the dark knight theme for windows 7 free download
Installing a theme on Windows 7 is straightforward, though some "third-party" themes require a small system patch to enable custom visual styles. How to install Custom Themes on Windows 7 batman the dark knight theme for windows 7 free download