If like me, your going to be deploying Windows 7 to a large number of different machines and configurations, you can create a number of different wallpapers and put them into the same folder, but name them the following (without the brackets):
Windows will then find your current configuration using calls to GetSystemMetrics. These values are used in the computation of the screen width (w)/height (h) ratio. For example, my desktop resolution is 1920x1200. The ratio, computed by the division of w/h, is 1.6:1.
The backgroundDefault.jpg image is loaded and stretched-to-fit when a resolution/ratio-specific background cannot be found. The other resolution/ratio-specific files are self-explanatory. If the background cannot be loaded (e.g. image physically too large, incorrect ratio, etc.), the default SKU-based image is loaded from imagesres.dll.
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